Hints for beginners

In an article published today on Practical Fishkeeping's website, Karen Youngs has some good advice for new (and not so new) fish keepers. Some of it is obvious to anyone who has done some reading, but other things were new to me.

Her first word of advice is not to stock tanks too quickly - wait for them to cycle. When I first kept fish, back around 1980, I was unaware of the concept. I don't recall it being in any of my fish books. When I returned to the hobby last year, it was something I was made aware of almost immediately - quite rightly, it's one of the first things they tell you are the pet store. That said, I still messed up with the whole cycling thing - it would have saved me (and my platies) a lot of stress if I had understood the time course a little better. I had fin rot and "shimmying" fish - because the tank wasn't yet cycled. While everyone wants fish as soon as possible, fishless cycling is much less stressful on the aquarist. But who really knows that right when they start off?

Once you have a tank that has cycled, you still need to add new fish slowly. More fish means a larger input of nitrogenous compounds. Since the bacterial populations will be limited by food availability, adding too many fish too quickly, even to an established tank, can cause a spike in ammonia or nitrite levels.

Her next piece of advice seems pretty straightforward as well - don't overfeed. But overfeeding is an elusive idea. If you read a pack of fish food they will say "no more than the fish can consume in three minutes". But that really depends on the fish. Some fish will take a couple minutes to even notice the food. Others will just keep eating. If I could get flakes that would float for three minutes, I suspect that my Macropodus would consume their own body weight in food.

Youngs has some interesting advice about feeding that I hadn't come across before. "How often should I feed my fish?" is a common question. Some people say three times a day, some people say once a day or less. Why such diversity of answers? Probably because it depends on the fish you're keeping. Youngs advises feeding small fish like tetras and guppies several times through the day. Larger fish should be fed less frequently. In addition, herbivores need to eat more often than carnivores. This is all pretty obvious once you think it through, and it's probably something a lot of people know intuitively. But again, it isn't something I remember coming across before.

She has some fairly standard things to say about lighting and algae, but again, says them well. Good advice on acclimating your fish, and on suitable tank mates. She advises redundancy when it comes to heating and filtration - two filters, two small heaters. Why small heaters? Because if one sticks on the "on" position, it won't heat the tank up too quickly. Common sense. Hadn't thought of it.

The last point she makes has to do with stocking levels. If you visit discussion boards, most people talk about the 1 inch per gallon rule as the upper level when it comes to stocking, which is why I was surprised when I read that an article in the February issue of Tropical Fish Hobbyist which suggested that you start a 10-gallon tank with "10 neon tetra-sized fish" (1 inch per gallon) but that you could eventually go to double that once your tank was well-established. Bending the rule a little - I'm sure most people do that. But going to double that? I was surprised. So it was nice to see Karen Youngs give similar advice

Nowadays with better filtration it is hard to give an exact figure, but PFK recommend the following:

Tropicals: 1” per gal/ 2.5 cm per 4.55 l initially, then up to a maximum of 2” per gal/5 cm per 4.55 l after six months.
Coldwater: 1” per gal/2.5 cm per 4.55 l.
Marines (fish and inverts):
1” per 4 gal/2.5 cm per 18 l.
Marines (fish only): 1” per
2 gal/2.5 cm per 9 l.
Ponds: 10” per 100 gal/25 cm per 455 l.

Getting that sort of advice from one source seemed iffy to me. Getting it from a second, independent source (and getting a more nuanced answer) makes me feel a little more inclined to integrate that factoid to my pool of knowledge.

Opening up a tank

A pet store in the City agreed to take the remaining Macropodus, leaving me with an empty tank. So what do I do with it?

There are a few options. One option is to try to turn it into a proper display tank. It's the most visible tank in the house, so it might make sense to try to make it as pretty as possible. But what I really want is a breeding tank, a place to try my hand at getting corys to breed. The question is - which ones do I try?

The biggest group, the six Corydoras trilineatus, are too young and don't seem to be thinking about breeding. The pandas are good candidates, as are the Cw008s, since I appear to have a male and a female, and they seem interested in one-another. I don't know what sort of conditions Cw008 would want for breeding, but it's worth trying the standard cory setup - regular water changes with water a little cooler than the tank. It's probably more important to give them a rich diet. The biggest challenge is probably to catch them without trashing the entire tank.

There's no guarantee that I'll be able to get them to breed, and if I do, if I'll be able to raise the fry. But I don't want to make the same mistake I made with the Macropodus - that left me with over 60 fry to find homes for. Since Cw008 (assuming that I have the ID correct) is less common, I'm guessing that there's an appeal in rarity. On the other hand, there's obvious demand for pandas - things with mass appeal are likely to be easy to get rid of.

Floating vegetation mat

Failure usually isn't something you want to broadcast to the world (or at least to the two or three people who might read this blog), but sometimes doing thins badly can have interesting results. Most of my plant introductions have resulted in at least a few plants that either get dislodged, or were never actually planted. These end up floating at the top until either you re-plant them, or scoop them out. But if you're like me, sometimes you choose neither option. As a result, one end of my tank supports a fairly large mass of floating plants - a mixture of Rotala, Lilaeopsis with some Ludwigia and who knows what else mixed in. It is anchored by the top of my tallest Hygrophila difformis plant.

The interesting thing about this set-up is that it brings corys right up to the surface. While they will swim up and down my Cabomba plants (which reach the surface of the tank as well), they don't spend much time on any particular plant. On the other hand, if they make it up to the floating mat, they can spend a good bit of time exploring it. Since the interior is too dense for any of my fish to get into, it's likely to provide predator-free space for small inverts. Since my tank is deficient in fish that use the upper portions of the tank, it's nice to see the corys active near the surface.

The pandas

The Panda corys (Corydoras panda) were really going crazy last night, chasing each other around the tank. At one point they were lying in what looked like the "classic T" formation that corys adopt when breeding, although there's nothing to suggest that they then went on to lay eggs. Nonetheless, I would really like to give them a chance to breed. I'm not really sure how I'd raise fry if I could get them to breed, but that's a problem I'll deal with if it arises. Based on what the guy at the pet store said on Saturday, there would almost certainly be a market for them. Of course, "market" is a relative term. Given the price they sell at, you wouldn't really be able to get more than trades off a pet store owner. Of course, the aquarium society does have auctions at their monthly meetings - that's an option that would generate actual cash. But first you'd need to convince them to breed.

Like anything of the sort, the information online is spotty and inconsistent. So short of buying a subscription to Ian Fuller's Corydoras World, it's likely to be difficult to get consistent information. They are described as both "easy" to breed and "difficult" to breed. Of course, it may be a matter of context - relative to guppies, they are hard to breed, but compared to some of the more difficult corys, breeding them may be easy. A couple people say that they produce small spawns - 5-10 eggs - but others say 100-300. Of course, spawn size could depend on a number of things, including whether you see the eggs before other fish eat them. It's also likely to be a function of the condition the fish are in, and may be related to water quality. I saw one comment about them liking a higher pH than is typical of corys (if true, that would be a bonus for me).

Macropodus breeding?

After building a nest and engaging in lots of mating behaviour, the Macropodus in the main tank seem to have reconsidered the issue. By morning there was nothing left of the nest but a few bubbles.

OKC fish stores

We took a trip to Oklahoma City to check out a couple LFSs (local fish stores). One of them I didn't like much, the other I really liked. And, when I offered, they said that they would be happy to take my Macropodus, and were willing to offer some store credit in exchange. Not sure I want the store credit - I shouldn't be buying fish right now - but they did have some corys I liked. They had some pandas (Corydoras panda), but they had sold the last of them just a little while before we got there. And considering that we got lost going there, if we had been a little quicker, we might have made it there in time, had we not gotten lost.

If we can get rid of the Macropodus, I'd really like to try to breed either the pandas or the Cw008s.

More Macropodus breeding

On the same day that I find someone interested in taking my young Macropodus, some of their siblings have decided to breed in the main tank. The largest male must have built a nest today - I don't recall anything like that earlier, but given its location in the tank, you never know.

When their parents bred for the first time (in this tank) the tank community was very different - there were a dozen or so platies, and four angels. Now there are no fish near the size of the male, and the female is at least as big as the other fish. There's also a lot more structure to the tank - the area around the nest is well vegetated.

The female has taken to chasing the other female Macropodus between matings, not that she doesn't do that anyway. In the past, after they were done mating, the parents established a two-tiered cordon around the nest, with the male keeping the female away from the nest, and the female keeping the rest of the fish away from the male.

I'll be curious to see how this works out.

Fish overpass

This setup in a (now-defunct) coffee house in Evanston, Illinois connected a pair of aquaria. It's a pretty amazing system - I want one!More pictures at thecontaminated.

H/T Zooillogix

Inverts

The plant tank (inhabited by cherry red shrimp, pygmy corys and Otocinclus) has a homemade sponge filter - a piece of sponge over the intake of a HOB (hang-on-back) filter. Since the corys spend most of their time under dense vegetation at the back of the tank, there's a lot of essentially predator free space for smaller inverts. The result of this is a steadily growing population of small organisms - probably cladocerans. While I'd have no problem harvesting them to feed to the fish in other tanks, I am concerned about shrimp larvae. I have no good sense of how small freshly emerged shrimp larvae are likely to be. I wouldn't want to end up turning them into fish food (or worse yet, simply discarding them after I clean the sponge filter.

Cleaning the sponge produces a huge crowd of these guys - and a layer of "dirt" (aka POM - particulate organic matter). I need to find some way to separate the inverts from this stuff. Right now I have them in a small cup floating in the tank. While this allows the dirt to settle out, it doesn't help much because the inverts prefer to feed in the POM. Is there some way to sink the cup but not disturb its contents to much?

Another of the original corys

This is another one of my three original corys. I believe that this is Corydoras sterbai. The first shot is a good one of his or her face (I suspect it's a female, but I really don't feel comfortable making a guess without a better sense of what they look like).
Here's a shot of its body. Unlike most other spotted cory's, it's got light spots on a dark body, rather than the other way around.
And here's a picture with one of my other corys - the one on the left I believe to be Corydoras trilineatus.C

Glowlight tetra

I haven't been able to get a good picture of the Glowlight tetras yet - this is about the best picture I can get, but it's a little blurry and more than a little washed out.

New corys

Here's a picture of three of my newest corys, which I believe to be Corydoras trilineatus, together with a kuhli loach.

Cw008

Thanks to my new pictures, Ian Fuller has opined that my corys (pictured in the previous post) are probably Cw008, not C041 based on the fact that the C041 has a deeper body and the sexes have almost the same pattern. The difference in pattern made me wonder at one point whether these were the same species, but their behaviour suggests that they are. At first, when I had three species among four fish (though I didn't realise it at the time), they tended to hang out together. When I added the pandas, the old ones still kept to themselves. Adding the [still unknown C. agassizii/C. ambiacus/C. melanistius/C. delphax/C. surinamensis or maybe something else] still didn't change behaviour in a huge way. But adding the C. trilineatus changed things - now all the corys are out fairly often. Increasingly, even the C. sterbai finds his way into the open. Only the poor lonely old C. aeneus remains hidden most of the time. More than anything else, those two need companions. But breeding the Cw008 would be awfully cool.

More cory pictures

I still don't know what they are, but I have a few more pictures of these corys.

Otocinclus

A picture of a nice fat Otocinclus in my main tank...

More Cory thoughts

My panda corys (Corydoras panda) have always been my most active corys - at night they tend to swim up and down the glass or plants. While I have always noticed that they swam "two and one" (two that stick close together, while the third tends to be on its own more), but it never crossed my mind until recently that the two that swam together might be a male and female. But that's what I think it is. Tonight I notice similar behaviour from the two "elegans-type" corys. If only I had some place to let them try spawing...

Corys

Last year, when I was just getting started, I bought a group of four corys that were labelled Corydoras aeneus. As best I can determine, the group consisted of one C. aeneus, one C. sterbai, and two unknowns. I believe that these two fish are members of the same species, and I'm pretty sure that I have a male and a female. But what are they? I finally decided to go through the Cat-e-Log at PlanetCatfish and try to come up with an ID. My best guess was C. pestai; poking around a bit, it appears that C. pestai is a synonym for C. elegans. Anyway, I posted a question over a PlanetCatfish - hopefully I'll have an answer soon.

Corys

Update: It turns out that my pictures aren't quite sufficient. Anyway, Kim M suggested that it might be "CW008 - "gold line elegans", or they could be C041 males". Both, in my opinion, are good candidates. Now to get some better pictures of them - including some pictures of the female.

Guyanese fish

My new Guyanese fish (Glowlight tetras, Hemigrammus erythrozonas) seem to be adapting to their new home. They are pretty fish, and they look good among the plants. Unfortunately, they aren't terribly active. Not only do they move around less than the Corydoras panda and Corydoras trilineatus, they actually use less of the tank (vertically) than do the pandas.

In their favour, the Glowlights tend to school, and when they move together, it's an impressive sight. That probably means that I need a lot more than six of them - the more there are, the bigger the impact. In addition, of course, they are also likely to be bolder in larger groups. Hopefully, as they get more accustomed to their new homes, the Glowlights will start using more of the water column. One can hope, anyway.

Glowlight tetras

Having lost my angels, I have been looking for some open-water swimming fish for my main tank. I have been considering tetras or White Cloud Mountain Minnows for the last couple weeks, but nothing really jumped out at me. So today I finally decided to go with Glowlight tetras, Hemigrammus erythrozonus. I wish I had made the decision after careful consideration of the biology and behaviour of the species, but I actually just narrowed it down to the ones I liked most, and based my final choice on the tank that had the healthiest-looking fish. That said, having spent two weeks looking at what was available locally and ruling out the ones that seemed too prone to fin-nipping, the decision wasn't just based on a whim. But neither was it the fulfillment of my quest for the "perfect" fish to fit my needs.

That said, I'm pretty happy with my choice thus far. They look pretty good in my tank, and they are schooling nicely. They're quite active and add colour to the tank. Unfortunately, they appear to prefer the lower third of the tank. They are venturing into the upper parts of the tank, which is encouraging - hopefully, as they grow more comfortable they will make more use of those areas.

The real Corydoras aeneus

Ian Fuller has an interesting article about Corydoras aeneus online at Practical Fishkeeping. The species was first described by Gill from fish collected in Trinidad - consequently, Trinidadian populations of C. aeneus are most likely to be true representatives of that species. Given their proximity, Venezuelan C. aeneus should be closest to the Trinidadian form. However, Fuller points out that there are three distinct Venezuelan forms: the typical form, C. aeneus 'Black' and a third form that Fuller considers a distinct species, C. venezuelanus Ihering, 1911. There are several other varieties that Fuller believes should be maintained as separate species. Some of these have been described as distinct species in the past.

Fuller finds it dubious that such different forms are the same species, especially since they are found in such far-flung locations as Trinidad, Argentina and Peru, in river systems that have been unconnected for millions of years. I suppose a good molecular study might be able to shed some light on the relationship within this group - at the very least, whether they form a monophyletic group or whether other species are nested within the group. If they are sister taxa, then the matter of whether they are the same or different comes down to the opinions of lumpers and splitters.

Changes

I threw the social organisation of both the main tank and the Macropodus tank into disarray yesterday. A friend asked for 8 Macropodus (to replace the fish he had lost during the ice storm). Picking out 4 large males was relatively easy, but picking out the four largest females (and being sure they were female) was more difficult. In the end, I decided that the best way to do this was to catch them all - that gave me a chance to look at all of them and get an overall count. This revealed something that I already knew - a couple of them smallest fish were not well.

I had removed one of the males in the main tank over the weekend because Camallanus worms were, once again, hanging out of him. This was obviously not a re-infection - these were worms that had survived the treatment. While I need to do a second round of treatment, I think I will go with levamisole (provided that I can track some down). Still, the idea of breeding drug-resistant worms did not sit well with me. Two of the others had holes in their sides. They had them when we got home from Christmas, and they had not healed. Anyway, the end result was that I euthanised five fish. Tempting as it was, I couldn't flush them or stick them in the freezer. Long ago, Brian said that there were two ways to kill a rat - one was humane to you, the other was humane to the rat. I decided that speed was of essence, and I decapitated them. Quick, yes, but very difficult on me.

Anyway, I added two males and two females to the main tank, and returned three males (and eight females) to the Macropodus tank. So now the males in the main tank are battling for status. The old male is twice their size, despite being their littermate. The older female though is only about the size of them new males, and is much larger than the new females. She is chasing the newcomers, both male and female.

In the Macropodus tank, the males seem invisible, while the females are trying to reestablish their order of dominance. I still have too many of them, but it's a move in the right direction. With more space and (hopefully) improved water quality, these guys might do some growing.

Restoring sight in blind cave fish

Ed Yong of Not Exactly Rocket Science writes

In this environment of perpetual darkness, the eyes of [the ancestors of blind cavefish (Astyanax mexicanus)] were of little use and as generations passed, they disappeared entirely. They now navigate through the pitch-blackness by using their lateral lines to sense changes in water pressure.

But there is a deceptively simple way of restoring both the eyes and sight that evolution has taken, and Richard Borowsky from New York University’s Cave Biology Research Group has found it. You merely cross-bred fish from different caves.

So how does this work? Obviously the lack of eye development is the result of different mutations in different caves. In different caves, different gene mutations resulted in the loss of eyes.

Arowana harvest

Matt Clarke at Practical Fishkeeping posted a series of pictures of Singaporean fish farmers harvesting Arowana fry from breeding ponds. The fish are mouthbrooders, so the fry need to be collected from their mouths. It's an awfully cool set of pictures.

Fish from Venezuela

After reading Gary MacDonald's fascinating article about Otocinclus-keeping in the February issue of Tropical Fish Hobbyist, I joined the TropicalResources bulletin board. And there I came across links to a fascinating set of fish videos on YouTube posted by Ivan Mikolji, who posts under the username fishfromvenezuela. He has an amazing set of videos, and really cool pictures on his website.

Here's one of his many videos. I really like the fact that you can get a feel for the species in its natural habitat. It would definitely be an asset to anyone setting up a South American biotope tank.

Changing tank profile

Over the holidays, I lost several fish. The losses were not random - as a result of the deaths of my angels and neon tetras, I have very little activity in the mid-level areas of the tank. In addition to that, my purchase of six more corys means that I have a large and active community of "bottom dwellers". Since corys are clearly my favourites, I can't say I'm terribly upset with the situation, but I'm not quite sure what I want to do next.

Given all the open water, I would really like a nice school of tetras or something of the sort. But two trips to the pet store have failed to turn up anything that really jumped out at me. I'm tempted to get some more angels, but I just don't want large fish - they really end up limiting your options when it comes to smaller fish. I'd much rather have a school of small fish than a handful of big ones.

Dedicated amateurs

The February issue of Tropical Fish Hobbyist includes a detailed article about recent changes in the systematics of Central American cichlids - what used to be the genus Cichlasoma. The author, Wayne Leibel, delves into the some pretty heavy-duty systematics papers and produces a very readable - and very detailed - synopsis of what's going on. For someone who appears to have no formal training in the field, he handles it amazingly well.

This is one of those things that fascinates me. While amateur botanists (and, for that matter, an awful lot of professional plant scientists and ecologists) tend to treat nomenclatural changes with disdain, fish keepers appear different - many seem happy to keep up with the "latest" names. Part of it may come from the fact that fish keepers are often on the leading edge of discovery of new species - newly discovered loricariid and corydorinid catfish are assigned L and C numbers while the hobbyists wait on systemtists to describe the species. But I suppose tropical fish keepers experience tropical diversity in a way that few other people in the temperature zone ever do. And it's a short step from "I want to know the name of my fish" to "I want to know the current name for my fish".

Juvie shrimp

My 2-month-old Cherry red shrimp appear to be pretty close to full sized but only a few of them are very red. Despite that, I noticed that at least one of them seems to be carrying eggs. I don't know for sure, but I am definitely hopeful. It would be reassuring to see them breed - the mothers of these shrimp were carrying eggs already when I got them, so I can't really claim to have "bred" them. If these guys breed, I will feel comfortable about the water parameters, and more hopeful about my ability to sustain a population.

Otocinclus and Corys

I found another two of the "trilineatus-type" corys at another pet store today. That gives me a total of six of them - hopefully it will get me some good schooling behaviour. I was looking for characins again, but once again nothing jumped out at me. Nothing but corys, that is. The two I bought were in a tank of "spotted Corydoras"; I have two of the other species, but I didn't want to buy too many fish today. I was also tempted to get some more Corydoras aeneus and maybe to finally buy some C. paleatus, but I managed to resist the temptation.

I actually went to the pet store in search of some Otocinclus - the February issue of Tropical Fish Hobbyist has a good article on them by Gary A. MacDonald of TropicalResources.net. MacDonald says that not only are Otocinclus very social fish (and recommends that they never be kept in groups of less than three), but when the groups exceed 12 individuals interesting dominance hierarchies emerge. Having read that, I felt the need to expand my collection - after all, I only have two in my main tank. Unfortunately, the pet store only had two left. Since I have no way of being sure which species of Otocinclus I have, I would rather purchase a bigger group - that way I'm more likely to get several of the same species.

Happenings

Having lost several fish over the holidays, I took the opportunity to add a few new ones. While I was interested in adding something new in world of characins, nothing of that sort caught my eye. I was tempted by a few barbs and some Rams, nothing really jumped out at me until I noticed some "spotted" corys in a tank (Corydoras trilinetus-type). There were four in there, so I decided to buy the lot.

Once I brought them home and released them into my tank*, they brought my resident corys to life. Adding some food helped, but the addition of smaller, younger, more active fish brought the whole tribe into action.

I saw at least three of my original four corys, and the five newer ones (two panda corys, two unknowns). I also saw both of my Otocinclus, and at least two of my kuhli loaches. So while I lost the angels, the fighter, my three neon tetras and a few Macropodus (0-2 males and 1-2 females), things look better than I initially thought. On the other hand, the plant tank seems empty - there seem to be a lot less than 9 pygmy corys, though the fact that they have moved from their original congregation spot makes it difficult to figure out how many there are.

*Yes, I realise that given my recent experiences I should have instituted a strict quarantine system. But, at this stage, I find it hard to care too much.

Holiday happenings

Updates after being away over the holidays. The good news is that I don't see any worms hanging out of my fish. It would appear that the fenbendazole worked. I need to re-treat the tank soon (it's recommended that you re-treat after two weeks) to kill any larvae that have re-infected the fish. Still, it looks good.

On the other hand, I lost a lot of fish. I came home last night to a house that stank of rotting fish. In the main tank, I lost both angels, my fighter, and all of my neons. I lost at least one Macropodus, probably more. I haven't determined what happened to the corys and the kuhli loaches - I saw one kuhli loach, all three of the panda corys, and several of the others. I see one Otocinclus, but I'm not sure about the second one. The water was horrible when I got home - I'm impressed that any fish survived such polluted water.

In the plant tank, I see a lot of shrimp, two Otocinclus and a few of the pygmy corys. I haven't seen many pygmy corys,; I'm hopeful, but concerned. The tank had very heavy algal growth - probably a consequence of having the lights on 24 hours a day for almost two weeks.

I haven't taken a good look at the Macropodus tank. There are at least a dozen fish in there, but it's very messy and overgrown. I haven't yet tried to tackle that one.

Treatment

While I was very optimistic about fenbendazole as a treatment option, I'm a little more worried now. After two days of treatment, I don't see fewer Camallanus worms hanging out of the fish. I am very concerned about whether the fish are ingesting enough of the drug, especially the smallest female Macropodus, which also seems to be the worst infected. I have soaked a mixture of foods in a fenbendazole suspension, and I'm hopeful that they are getting enough of it, but the only way I have of monitoring the treatment is by looking at the worms hanging out of the fish. They still appear red and healthy, which isn't a good sign. This is the final day of the treatment course, so I was hoping for some visible results. "TheGreatBlueDiscus" had visible results after 36 hours, but since he was treating his fish twice a day, that amounts to three treatments.

Since I won't be able to continue the treatment over Christmas, I'm seriously considering euthanising the Macropodus. Not something I would want to do, but I can't afford dead fish floating around the tank for several days (there's only so much my plague of snails can handle).

Timeline of infection

A parasitic nematode like Camallanus needs to get into the aquarium from somewhere. I've been thinking about possible paths of infection. According to Levsen and Berland (2001) Camallanus cotti takes 11 days to fully develop in its copeopd host, and then another 34-42 days to develop after it is ingested by a fish host. Presumably the adult feeds for at least a few days before it extrudes from the anus of the fish and starts releasing larvae of its own. Levsen (2001) found that it took a minimum of 62 days and a maximum of 110 days for visible signs of the parasite in a system with monoxeny - direct (fish to fish) infection. Since I first saw signs on the worms in mid-December, they became infected somewhere between early September and early November. That said, I first noticed the worms last weekend, and once I looked there were worming hanging out of several Macropodus.

In that time period I bought (and didn't adequately quarantine) quite a few fish. The fighter is an unlikely culprit - not only did we buy him too recently, he also shows no signs of infection. The pygmy corys are also unlikely, since they have never been in the main tank. On the other hand, the plant tank has a population of copepods, so I would only have to introduce the copepods, not actually any fish. It's reasonable that Camallanus was introduced with infected copepods that came with the Java moss. The timeline is reasonable - about 55 days. I also transferred a couple larger corys from the plant tank to the main tank, and an Otocinclus. They are also potential sources of infection.

There are, of course, other possibilities. I bought three batches of neon tetras this Fall, and had remarkably high mortality. I also bought some ghost shrimp. The ghost shrimp themselves are unlikely vectors - I have not read about Camallanus infecting shrimp, although there's a slight chance that they were using them as secondary hosts. The neons, on the other hand, are another story.

I bought my first batch of neons back in early September. Four of the five died within two days, and that was followed by a wave of mortality: a fighter, two Angels, two platies and a couple Macropodus. It seems pretty obvious that they weren't the ""cleanest" of fish. The extra burden of Camallanus infection could be blamed for the death of the neons (if you're already feeding parasitic worms, you have fewer resources with which to handle stress), it seems unlikely that transmission of the Camallanus larvae could have resulted in such rapid mortality among the other fish.

While I initially blamed the pet store, the deaths of the other fish led me to wonder whether something had gone wrong with my water, and that the timing might have been coincidental. Anyway, the sole survivor remained in the tank, seemingly healthy, but with a shrunken abdomen (which was always a cause for concern). He died a couple months later, after I bought some more neons to keep him company.

I'm most inclined to blame the neons (or more specifically, the one neon). And while I could do a lot to improve my quarantine procedures, segregating new fish for 2 to 4 months just isn't something I can do at present. While I hate the idea of medicating new fish as a precautionary measure, I can see why people would do it.

1. Levsen, A. (2001). Transmission Ecology and Larval Behaviour of Camallanus cotti (Nematoda, Camallanidae) Under Aquarium Conditions . Aquarium Sciences and Conservation, 3(4), 315-325. DOI: 10.1023/A:1013137801600
2. Levsen, A., Berland, B. (2002). The development and morphogenesis of Camallanus cotti Fujita, 1927 (Nematoda: Camallanidae), with notes on its phylogeny and definitive host range. Systematic Parasitology, 53(1), 29-37. DOI: 10.1023/A:1019955917509

First casualties?

While the Camallanus still appear well (there are still red worms hanging out of most of the Macropodus), one of the male Macropodus died. Was it worm-related, meds-related or just coincidence? I'm inclined to think it's something other than coincidence. After all, the only visibly infected fish are the Macropodus, so I'm guessing that they are more susceptible to the Camallanus.

It makes me wonder whether there's a stress component. The Macropodus are likely to be the most stressed fish in the tank, since their struggles for dominance consume a lot of their energy. Interesting thought.

Camallanus biology

One of the challenges of home diagnoses is "getting it right". Based on the University of Florida IFAS Extension document (Yangong 2006) on nematode infections in fish, a diagnosis of Camallanus infection seems reasonable. But, like any biologist, my first question is: what species? Is there only one species that you tend to find in freshwater aquaria, or are there many?

According to Yanong, Camallanus requires a secondary host, usually a copepod. I suppose a moderately planted tank with driftwood has lots of room for copepods, even if I can't see them. There are enough hiding spots for them in there. So I'm guessing that control of secondary hosts really isn't an option.

"The dreaded Camallanus worm"

On Sunday I noticed something red and spiky protruding from the anus of one of my female Macropodus in the main tank. When I looked at them carefully, I saw something similar on one of the males. While I had never seen anything of the sort before, it was easy enough to recognise based on the descriptions I had read online - my tank was infected with "the dreaded Camallanus worm". A quick Google search reveals two things - one, that aquarists dread this worm (a genus of parasitic nematodes), and two, that there are two fairly well-established treatments: fenbendazole and levamisole. Fenbendazole is a common dog dewormer, and levamisole is apparently used for pigs. Fenbendazole was available at the pet store locally, so I went with that. However, levamisole is probably easier to use, since it can be applied to the water, and is usually effective with a single treatment. Fenbendazole needs to to ingested by the fish, and involves a three-day treatment cycle, followed by another treatment two weeks later. Since the fish have to ingest the drug, the issue of dosage becomes very complicated. On the other hand, the more powerful a drug, the more suspicious of it I am. I was reassured by the low level of warning on the fenbendazole package as well.

Based on what I could find online, I decided to make a solution (or suspension) of the fenbendazole and soak bloodworms in it. For good measure, I also added some sinking pellets to the mix. The fish at both quite happily, so it does not seem like the drug made the food unappealing (either that, or it didn't soak in well enough, which is a concern of mine).

Like everything else in the world of fishkeeping, the major source of information out there is the bulletin boards. And like everything else, I'm hesitant to trust them. I'm glad I came across this University of Florida IFAS Extension document. It was also nice to find this essay at PetFish.net - most people use levamisole, so it's nice to have something against which to compare my own experience.

Main tank

Yeah, I know...it barely deserves the designation "planted tank", but that's without carbon dioxide injection or "adequate" lighting.

Experimenting with Excel

I bought a bottle of Seachem's Flourish Excel - apparently it's basically glutaraldehyde, which serves as a source of bioavailable carbon for aquatic plants (but not algae). It's also supposed to function as an algaecide, especially at higher concentrations, although it isn't actually marketed as such (see Seachem's FAQ; there's also a lot of talk about this on discussion fora).

While I'm terribly curious about the mechanism of action of glutaraldehyde (or whatever it may break down into), I'm mostly curious about whether the plants in my main tank are CO₂ limited. My light levels are well below what's recommended, but when people talk about planted tanks, they talk about light and carbon dioxide. Given my current light levels, would my plants be able to utilise additional carbon? I hope to find out.

Not shrimp?

I feel fairly confident that the smaller organisms swimming around my plant tank are not baby shrimp. I'm guessing they're some sort of cladoceran that got introduced either with the plants or the fish or shrimp or, for that matter, on a rock, in some dust... The unusual thing probably isn't getting things like that into your tank, it's a matter of their finding predator-free space. The current inhabitants of the tank (Cherry red shrimp, pygmy corys, Otocinclus) aren't going to both organisms that stay out of their way. Adding a prefilter also makes the tank more friendly to smaller organisms.

Betta bulbs

It's been about six weeks since I planted the "Betta bulbs" (Aponogeton sp., allegedly A. ulvaceus), so whatever's going to grow has probably grown. Apparently I planted four in the main tank, one in the Macropodus tank, and two in the plant tank.

They grew well in the plant tank. After about two weeks, one of the bulbs had sprouted, and after another week a flower spike broke the surface of the water. While the first one didn't expand, the plant has produced another four in rapid succession. The young inflorescence looks like the top picture. As it expands it ends up looking more like the lower image.

Shortly thereafter, the second bulb in the plant tank started growing, and it too has produced a succession of flowers. Both plants have also produced floating leaves.

Things were a bit different in the main tank. One of the bulbs floated up fairly soon, apparently dead. A second one eventually made it to the surface, and appears to be dead as well. I'm not entirely sure what happened to the other two - there's one plant that's either a young Aponogeton or a Cryptocoryne sucker, and another leaf that could be a second bulb. In both cases, the plants are small and could easily be something else. I haven't seen any sign of the bulb in the Macropodus tank, but that tank has become so heavily overgrown (since I upgraded from incandescent to compact fluorescent lighting) that I'm really not sure that I would be able to find it if it were growing.

Nineteen

Just counted 19 juvie shrimp (and that doesn't include the little dots that are still flitting around). My best prior count was 15. On the other hand, I haven't seen the last adult for several days - I'm getting a little worried about him.

Using OpenID for comments

I added the option of using OpenIDs to comment on this blog, per phydeaux3's blog post. So it should now be possible to leave comments using AOL/AIM, LiveJournal, TypeKey, WordPress or other OpenID logins.

Phydeaux3 also has instructions on how to alter the settings on to allow this on Blogger.

Restricted aquatic plants

As I mentioned in the past, I was surprised to realise that one of the most widely recommended aquarium plants was a federally listed noxious weed in the US, and may be illegal to possess in Oklahoma. Today I came across a notice that possession of Cabomba carolinina is illegal in Maine. With a tankful of an unidentified Cabomba sp., I grew a little concerned. But it doesn't fall on the federal noxious weed list, and it doesn't appear to be on the Oklahoma list. Still, there are a few important thoughts in all this:

• Never release anything from your aquarium into the wild. (That should be pretty obviousl but it isn't).
• Dispose of all plant material with care. While that is especially true in warmer climates, aquarium plants can obviously even be problematics as far north as Maine.
  
• If it grows like a weed, it probably is a weed.

Shrimp skins

After losing three of my four adult shrimp, I was rather concerned when I started finding what looked to be dead juveniles. In the first few cases, I noticed that they seemed rather thin and insubstantial, but after a while I concluded that they were probably shed carapaces, rather than dead shrimp.

That said, some amount of juvie mortality is to be expected. I'm still thrilled with the fact that I ended up with at least a dozen offspring, despite the fact that the tank was very unsuitable for shrimp when they first hatched; the initial setup included a female platy and an unprotected filter intake. On the other hand, the filter box may have provided a refuge/nursery for the young shrimp - since the filter pad was very dirty and the flow was only moderate, it might have been a perfect, food-rich environment for them. Makes me curious how well they tolerate the water flow and whether light is important for their development...

Shrimp

Last week, I lost three of my cherry red shrimp, perhaps as a consequence of a large swing in temperature. I still have one of the original adults (a male, presumably) and at least a dozen juveniles (the largest of which are almost the size of the male).

Over the last few days I have been seeing some tiny organisms swimming around in the tank. Initially they were just at the limits of my perception, but by today they approaching a half a millimetre. Are they some sort of small crustaceans which were introduced with the plants but are finally reaching population sizes that allow them to be noticed, or are the baby shrimp? It's possible that one of the females was carrying eggs that hatched before she died - but I'm surprised that I would have missed something like that. Of course, it's also possible that one of them was carrying eggs when she died - and that some of those eggs managed to survive untended.

I suppose I shall find out eventually whether these are shrimp or something else. Shrimp would be cool. A spontaneous Daphnia population would also be kinda cool.

Aquascaping, part IV

One of the common complaints about aquarium plants is that, as they grow taller, they lose their lower leaves. This is especially true in lower light situations. Most people will recommend trimming the plants, removing the bases and replanting the tops. In a mature, heavily-planted aquarium that's probably the right idea. But when you are trying to grow a stock of plants, it isn't the best idea - in that case, the objective is to maximise your stock of planting material.

When you prune a plant, it will normally produce new shoots from an existing axillary bud. These buds are located at the point where the petiole of a leave joins the stem (or where one used to be before the leaf was shed). When a stem it pruned, one or more axillary bids start to grow. This can produce a bushier plant, but the appearance isn't always what you would want, since you end up with a distinctly smaller shoot coming off of a larger stem.

If the branch develops from the topmost axillary bud, there's a chance that it will develop into a new leading stem. But will that really create the desired look? This is far more important for foreground plants than it is for background plants, of course. From this perspective, it seems like it would make sense to cut plants back are low as possible, leaving an almost indistinguishable old stem. The obvious problem there is the danger of cutting it back too far. The plant can only produce new stem material if it has the resources to do so. How little is enough? That's not only going to vary from species to species, it's also going to vary from individual to individual. A small scrap of Java fern leaf will grow into a new plant, but how little Ludwigia stem (to use the example in these pictures) will produce a new plant?

There is, of course, another problem as well. Large, healthy plants do not appear out of nowhere. If you prune too heavily you may end up with a large stock of skinny, sad-looking plants.

Aquascaping, part III

Adding rocks created a little more dimension to my tank, but it still wasn't enough. Around the same time I set up the plant tank (or perhaps it would be better to call it a plant nursery, since that is how I originally envisioned it) and purchased a few more plants. Perhaps it was serendipity, but I got some new Cabomba and Water wisteria (Hygrophilia difformis), together with some new Ludwigia. Without high-grade lighting and CO₂ injection, I am not going to be able to establish the sort of super-dense garden tanks that are so popular these days. I shouldn't be trying to mimic those setups - I need to work on producing the best aquascape I can, given my constraints. But I can still learn from them without resorting to a crude caricature, a child's imitation.

Although it didn't start well, I have been very happy with Cabomba. Initially it became very stringy, elongating its internodes in a push for the surface of the water. But now, it has thickened up pretty well and filled out. But trimming and replanting the tops, I have the makings of a nice little Cabomba forest. The cut stems have resprouted, and a few uncut stems have also sprouted. While it doesn't seem to match well with modern ideas about aquascaping, it has a "natural" feel to me, the feel of a macrophyte-filled lake. The water wisteria were planted in an area behind the driftwood, adjacent to the smaller of the Echinodorus. The divided leaves emerge from an area dominated by shorter plants with narrow, elongate leaves. I like the effect, but it's a little asymmetrical.

I recently read an article about Dutch aquascaping. While the practice stresses garden-like layout and terraced arrangement isn't something I plan to implement, I was struck by the idea of using "pathways" to create an illusion of depth. I really think that's something I could make use of.

Dietary preferences

It's interesting to see how fish differ in their dietary preferences. I bought some frozen Tubifex worms a few weeks ago, and offered them to my fish. The occupants of the Macropodus tank immediately went crazy over the stuff. On the other hand, in the main tank no one but the Panda corys and the neon tetras showed much interest in it initially. Over time most of the other fish have learned that this is food, but only the pandas would go after it when anything else is present - and the Macropodus still don't realise that Tubifex worms are food. It's odd, given that their siblings are the ones that are most eager to eat it.

I noticed that the leaves of the 'Water wisteria' (Hygrophilia difformis) in the Macropodus tank have been chewed on, so I decided to see how they would respond to blanched spinach. Again, unlike their siblings in the main tank, they went after it enthusiastically. So finally, I offered them blanched zucchini. Twelve hours later it sits untouched at the bottom of the tank. I also added some zucchini to the main tank for the Otocinclus. Much to my surprise, one Macropodus and one cory took a liking to zucchini.

I find it interesting the way that dietary preferences differ both among individuals and within the "culture" of a tank. The Macropodus in the main tank and those in the Macropodus tank are "littermates" and full siblings. And yet they differ in terms of their willingness to take food items. Competition for food is more intense in the Macropodus tank, so it isn't surprising that they would more readily take any food item offered. But why do their siblings in the main tank totally ignore the same food item? The zucchini issue shows another level - that of "personal" food preference.

While I added zucchini primarily for the Otocinclus, the only other fish I have seen eating from it was one of the kuhli loaches.

Shrimp mortality

I found two of my cherry red shrimp dead today. While I'm sadden by their deaths, I am more concerned by the fact that I don't know what killed them. Was it just chance? I doubt it - one death at random wouldn't surprise me, but two seems to be a bit much of a coincidence. My water parameters seem to be ok. The only real notable change is the weather - temperatures fell from about 27°C/80°F on Monday to about -3°C/27°F on Tuesday night. While I have a heater on the plant tank, it lacks a cover (and the cat pushed the shade away from the window, which probably exposed the tank to draughts).

So is it the weather, water quality, a pathogen, or just coincidence? I wish I knew.

Main tank

Aquascaping, part II

Over the course of the next few months I added a few plants - most notably a couple Spathiphyllum plants - not true aquatics (although I didn't know that when I bought them), but they can survive for extended periods underwater - and a couple more Echinodorus. The Spathiphyllum anchored the back right corner of the tank, while the new Echinodorus plants occupied spaces on either side of the filter intake.

Echinodorus, the "Amazon swords" are an interesting - and diverse - group of plants. My original ones were a tall species - once they get large enough, they produce emergent leaves. They would make nice pond plants and would be good in open tanks, but they really aren't idea for the setup I have unless you are willing to do some major pruning. From what I have read, pruning the roots is probably the most efficient way to produce a smaller plant. The corys excavated the root ball of one of the large Echinodorus, which had the desired effect of dwarfing the plant (for the time being, anyway). I may trim the root mass again in a few months, or try dividing the plant. The other species of Echinodorus is very different - it's really the idea plant for my setup. It has shorter petioles and more lanceolate leaves. Ever since I switched to 6500 K plant bulbs it has produced smaller, denser leaves. It makes a good background plant, filling space at the back of the tank. Since the plants came with plantlets (flower spikes which had either failed to break the surface or, more probably, been submerged when the plants were prepared for shipping), I planted them in what became the Macropodus tank. They seem to have done well in that overgrown, badly overstocked tank. Since I upgraded the lighting in there (from the original incandescent bulbs to compact fluorescent) they seem to be doing better. Unfortunately, conditions in that tank favour algae growth (no snails, excess nitrates) so the leaves tend to have a lot of epiphylls (plants that grow on the leaves of other plants; in this case, algae). During that period I also received a number of plants from a friend. That increased my species diversity, and gave me some new options. I also bought a piece of driftwood. Eschewing the normal rules, I placed it to the from of the tank where it provided cover for my kuhli loaches in a place where they would be visible to me.

Unfortunately, I also suffered an ich outbreak. Since I was unwilling to use any of the commercially available ich treatments (most are based on malachite green, a carcinogen), I decided to go with high temperature + salt. While this succeeded in clearing up the ich problem, it also wreaked havoc on the plants. The entire experience dampened by enthusiasm, and the issue of aquascaping was put on the back burner.

Things changed again late in the summer. As is customary, we went Petosky stone hunting when we were in Michigan, and walking along the pebble beaches I collected a number of other interesting rocks. When I got home I gave some of them a shot in my aquarium. I wasn't sure about their suitability - if they were carbonate based they would probably raise the hardness significantly - but I thought it was worth a shot. I excluded the glittery rocks out of concern that they might contain pyrites (which could yield suphuric acid in the tank) and the Petoskies (pretty, but I knew them to be calcite). I figured I could take them out if they increased the hardness too much.

Adding the rocks changed the tank substantially for the corys. Prior to that, their use of space was largely governed by the availability of cover. Large, open areas to the front of the tank were rarely used during the day. Adding rocks along the bottom of the tank creased more usable space for the bottom-dweller. Coupled with additional substrate in the back left corner of the tank, there was the beginning of an aquascape. Since then I have added a few more plants. Establishment of the plant tank also created a source of cuttings that I could use in the main tank. Unfortunately, the first species I focussed on proved to be a poor choice.

Aquascaping, part I

When I first set up my tank, I was interested in having plants, but I had no real concept of "aquascaping". There was only a limited selection of plants, and I didn't have any idea of how densely I should plant the tank. In a certain sense I was lucky - I didn't waste money planting a dense garden which would have promptly died through lack of light and carbon dioxide.

My initial setup was deficient in more ways than I really want to discuss. The Echinodorus plants were a good focal point on one end of the tank. Since they were sold singly it was pretty easy to plant them properly. The Java ferns were, similarly, easy enough to separate, although I didn't know that you were supposed to keep the rhizome above the substrate. Even more problematically, I had no idea that I should separate the bunched plants. Had I separated the Ludwigia, Bacopa and Myriophylum I would have had a more garden-like arrangement, and may well have had better survival rates. Other problems included the total lack of non-plant features on the bottom of the tank and no real sense of what my ultimate design goal.

With no goal it was easy to end up headed nowhere.

The cave

This is one of my favourite features of my aquascape. It's a bit less impressive viewed at the level of the tank, but I still like the look.

It's probably pretty apparent that the Cabomba could use a bit more light. The microsword (Lilaeopsis brasiliensis) in the foreground was uprooted by the fish (probably the kuhli loaches) and I replaced it with some small Hygrophila polysperma (which I removed when I decided to eliminated the species from my tanks).

Shrimp

I counted at least a dozen baby cherry red shrimp yesterday. The largest of them is 11-12 mm long (plus tail).

And in the main tank, I have seen a ghost shrimp twice in the last couple days. That was quite a surprise - I didn't really think any had survived the initial introduction.

Photoperiod and plant growth

As I mentioned in my last post, conventional wisdom is that aquarium plants "can't use" light beyond a 10-14 hour photoperiod, and anything beyond that ends up going into algal growth. Explanations like that don't make sense to me...is photosynthesis supposed to shut down at a certain point? But that doesn't mean that the observation isn't true (something this well established is likely to be based on fact), but I'm curious about the underlying mechanism.

In a 1998 paper, E.B. Jensen and B. Veierskov looked at the effect of photoperiod on photosynthesis in tomatoes. They found that increasing the length of the photoperiod from 8 hours to 16 hours caused the carbon dioxide assimilation rate (i.e., the rate of photosynthesis), but photosynthetic rates fell with a 23.5-hour photoperiod. (Open bars in the figures). Starch and sugar concentrations showed a similar pattern.

This is interesting - an increase (and then decrease) in the rate of photosynthesis. The paper provides a mechanism for this difference - changes in chlorophyll a, chlorophyll b and carotenoid levels probably explain these differences.

Protein levels increased sharply at a 23.5-hour photoperiod, as did ethylene production (ethylene is a plant hormone which is produced in response to stress). The transgenic pTOM13 plants (shaded bars) have a reduced ability to produce ethylene. Jensen and Veierskov concluded that ethylene production is likely to be the cause of the "chlorosis, leaf distortion, purpling of older leaves and growth reduction".

So what does this mean with regards to the original question of how long to leave the lights on in your aquarium? It's a start - the idea that overly long photoperiod can damage plants is reasonable. But you can't readily translate that into the specific requirements of even the most common aquarium plants. More importantly, saying that excessive day length harms plants isn't the same as saying that it encourages algal growth. While plant growth appears to suppress algal growth (or so says another piece of conventional wisdom), at this point it seems more likely that algal growth would either be an indirect effect (maybe increased nutrient availability driven by decreased plant growth?) or a direct effect unrelated to plant growth (for example, algal growth may increase continuously with photoperiod, while plant growth falls off once it exceeds some threshold, creating a relative advantage for algae).

I need to keep looking.

1. Jensen, E.B. and B. Veierskov. 1998. Interaction between photoperiod, photosynthesis and ethylene formation in tomato plants (Lycopersicon esculentum cv. Ailsa Craig and ACC-oxidase antisense pTOM13. Physiologia Plantarum 103:363-368.
   

Photoperiod

One of the bits of conventional wisdom that floats around aquarium articles and message boards is that tropical plants, which are adapted to a 10-14-hour photoperiod, and that anything beyond that is a bad idea. This article is a typical example:

Leaving the lights on 24 hours a day while you were away was not a good idea. Most of the plants we use in the aquarium come from tropical areas, and are adapted to about 10 and 14 hours each of day and night. At 2 to 3 watts per gallon of fluorescent light, a 12-hour photoperiod works well for me. This can be adjusted based on lighting intensity. In no case does it make sense to extend the photoperiod much beyond 14 hours. Most higher plants will stop photosynthesizing at this point, while the algae will take full advantage of this situation.

But is this really the case? Does photosynthesis shut down after 12 hours? Possible, but what's the source? I need to figure this out.

Equipment maintenance

Over time, I noticed that the water flow on my filters declined. In the case of the Macropodus tank, I wasn't too concerned - quite frankly, it's easier to ignore that tank than it is to stress about the fact that there are 40 fish I don't want (but don't know how to get rid up) taking up one of my tanks. Then I noticed that the biowheels on my main tank wouldn't turn. I cleaned the filters, I cleaned the intake, but nothing seemed to work. If anything, things got worse. Finally, I noticed the water flow decline on the plant tank. That started to bother me - the filter was only a few months old. Was the motor burning out already?

Finally, I decided to take it apart and clean it properly. Only when I took it apart, and then looked at the set-up and maintenance instructions, did I realise what the problem was. It was amazingly easy to do. The next day I did the same for the other tanks, and I was amazed at the water flow in the main tank. I had totally forgotten what it was like.

Of course, a few seconds on google could have told me that I needed to do that. Oh well...

On breeding corys

My fascination with corys dates to my childhood. I bought my first corys when I was 11 or 12. I had no idea what they were, but eventually I was able to match them to illustrations of Corydoras aeneus which, as it turns out, is native to Trinidad. After we moved the corys ended up as the sole denizens of their tank, alone and ignored. So it was much to my surprise that I found four or five of them swimming around in a tank where there had only been three. (And I use the word "tank" loosely - it was a very large old enameled pot that had once been used to boil diapers.)

Ever since, I have had a fascination with corys. They were among the first fish that I bought when I got back into fish keeping this year, and I now have five species of Corydoras. While I would be happy just collecting them, I have an urge to replicate what I once achieved through chance and neglect.

Most descriptions of corys mention spawning - this species is easy to spawn, that one is very difficult. In addition, they refer to the "classic" T configuration. Some people will even mention that the male forms the top of the T, and the female faces him. But I was never able to visualise it, and no one bothered to provide illustrations. Thankfully, I have finally come across an article with pictures. Ian Fuller's article So you want to breed corys? provides just that - a picture of the "classic T-position" (scroll down pretty much to the bottom of the page). On seeing that, my reaction was "oh, really?" Have I seen that before? I may have. It has a terribly commonplace look, the sort of thing I would not have identified as spawning behaviour. A while ago my first corys (species unknown) did a lot of what looked like spawning behaviour. I was looking for the T position, but never saw it (I was looking for something more dramatic). In my main tank eggs would probably be snail food and fry fish food. But it makes me hopeful that I could induce them to try a second time.

More pygmy corys

Having stripped about half the biomass out of my plant tank, I became reacquainted with the pygmy corys. I started out with ten in the tank; I'm not certain how many of them survived, but I'd say there's a minimum of nine. When they were first forced out into the open they became very skittish, but they seems to be settling down a little. So the thought of getting them to breed crossed my mind. Unlike Macropodus, I suspect there's a market for these fish - I have only seen them once at local pet stores. While I may not be able to sell them, I suspect I could get the one independent store to trade some.

I googled breeding pygmy corys and got several promising hits. While they all agreed that the fish weren't difficult to breed, they differed markedly with respect to their thoughts on the idea setup. Ian Fuller at Pets Parade ("Britain's Biggest Petshop") says he uses four males and two females for breeding. However, he is writing about all five "pygmy" species in the article (Corydoras cochui, C. gracilis, C. habrosus, C. hastatus, C. pygmaeus and C. xinguensis), so that may not be the place to look for something overly specific.

Writing at AquariumFish.com, Mike Hellweg gives a very detailed description of C. pygmaeus breeding behaviour. He notes that, although they spawn in a group, each male "stakes out" a specific female and breeds only with her. Consequently, he goes for balanced sex ratios in his breeding tanks. On the other extreme, Kaycy Ruffer at PlanetCatfish recommends "at least one female to six males".

There's a wealth of fish keeping advice online, but the problem is that people simply say what works for them. All three of these appear to have successfully spawned pygmy corys. None of them given any indication that they have experiments with different setups, and only Mike Hellweg explains why he made the decisions he made. It's like reading testimonials for "alternative medicine". Sure, people took the product and got result x, y or z. But how do you separate coincidence from successful practice? Therein lies the problem.

Irresponsible plant dealers

Almost every fish store I have been to sells non-aquatic plants as aquarium plants. In some cases the plants are non-aquatic, but can persist under water for months. If purchasers were warned, I could see a case being made for some plants (like Spathiphyllum, which is apparently good with very boisterous fish). It's irresponsible to see plants like that to unsuspecting aquarists. I was quite disheartened by my initial attempts at establishing plants (although salting the tank to deal with ich was probably the biggest plant killer).

It's one thing to sell your customers something that will never work. It's quite another to actually make them accomplices in lawbreaking. While I have not seen Hygrophila polysperma for sale in a fish store, it's available online. There are also reports that it is sold in pet stores. More disturbing is that fact that aquarium plant books published by reputable publishers say nothing of the fact that transporting the plant requires a permit, and possession in some states is a crime. Granted, there's no reason for a British publication to say anything about this unless they are producing an edition for the US market.

Destroying the plant tank

I recently discovered the Hygrophila polysperma is listed as a federal noxious weed, making it illegal to transport without a license. It didn't occur to me to check state laws. Turns out, it appears to be illegal to possess the plant in Oklahoma. So, sadly, I decided to get rid of it.

In three of my tanks that isn't a huge deal - while it was in all of my tanks, it wasn't a major component of the flora. In the plant tank, on the other hand, it was clearly the dominant plant. When I established the tank I took a lot of small bits and planted them with the hope of getting good stems to establish elsewhere. So not only was there a lot of biomass, there were an awful lot of stems of the stuff. Removing them is not only traumatic to me, it's also hard on the fish. After living life well-hidden, they are not out in the open. And I have to start over on my planting ideas.

The other challenge, of course, is disposing of the stuff. Two options are not available - sending it down the drain or throwing it in the garbage. Luckily, it has never flowered, so I don't have the worry of killing seeds. Still, just to be on the safe side, I decided to microwave the plant material for five minutes, and then let it dry completely.I can't see how it would survive that. Now the next challenge - getting the "plant tank" back to the point where it deserves that name.

Update: The challenge, I think, isn't killing the plant, it's finding all the bits. The very characteristics that make Hygrophila polysperma a problem plant also make it hard to eradicate - it can sprout from small pieces of stems floating somewhere in the aquarium (or body of water).