Friday, 28 November 2008


Six weeks ago I purchased a pair of albino Kribs (Pelvicachromis pulcher) - I've always wanted dwarf cichlids, and the new tank was in need of occupants that could handle "semi-aggressive" tankmates. (To be honest, while Macropodus are often described that way, mine have always been extremely gentle, inoffensive fish.)

Within a week the kribs started excavating a hole below a piece of driftwood. The female then started spending a lot of time beneath the driftwood. Cool, I thought, they are interested in mating. The second week passed, and the female spent a lot of time out of site. I didn't give it too much thought. Then at the start of week three I came home one day to notice both kribs were out on the open, keeping close to the bottom of the tank. As I looked a little closer I noticed movement beneath them and realised that they hadn't "considered" spawning, they had gone ahead and done so. Given that there were four large Macropodus in the tank with the kribs, I immediately became concerned for the safety of the fry. The kribs seemed to be attentive parents and the Macropdus had little interest in what went on at the bottom of the tank, but it still seemed only a matter of time until the krib fry turned into Macropodus snacks. It was thus quite a surprise when I realised that the kribs were quite effectively bullying fish that were 2-3 times their size. Even the (rather small) female krib was able to chase the Macropodus males off when they ventured too far down the water column.

Over the past three weeks the fry have grown remarkably quickly. Initially they foraged in a tight bunch on the bottom of the aquarium, attentively guarded by one parent (while the other parent patrolled the tank). As they got bigger they started moving away from the bottom, higher up the water column. On at least one occasion the parents seemed unsure what to do when half of the babies were on top of a piece of driftwood while the other half were foraging nearby on the bottom of the tank. Over the last week the fry have spread out and no longer forage as a group. They have also reached a size where they are no longer at much risk from the Macropodus - one of the fry ended up high enough in the water column that it attracted attention from one of the female Macropodus. She swam over to check it out, but then turned away. I'm guessing it was too big for her to consider it food.

Now what do I do with 20 kribs?

Friday, 15 August 2008


At some point, every aquarist has ask the question "how many fish should I put in my aquarium?" Conventional wisdom says "one inch of fish per gallon". Earlier this year I blogged about two articles that challenged that dogma, one in Practical Fishkeeping and the other in Tropical Fish Hobbyist. In each case, they suggested that a well-established tank could support twice that level - two inches of fish per gallon.

While territoriality and aggression can play into the number of fish you can keep in a tank, those are species specific considerations that overly any basic rule of thumb. Far more basic is the issue of oxygen supply. While certain fish depend on gaseous oxygen (the best known being the anabantoids), most fish depend on dissolved oxygen. Too many fish and too little surface area will lead to problems. The other issue is "bioload" - the production of waste products by the fish. These include nitrogenous compounds and organic waste. Ammonia and nitrites are harmful at relatively low concentrations; they tend to be a problem in new tanks, but can also build up in established tanks if the biofiltration crashes. Chances are though, if the biofilter crashes, even a moderately stocked tank will run into major problems. Nitrates, on the other hand, are only a problem at higher concentrations, but unlike ammonia and nitrites, they are not broken down by most biofilters. Organics are a separate issue - one that doesn't seem to get all that much attention. Some people specifically add organics ("black water extract") to their tanks. Others stress the importance of water changes to control the levels of organics. The simple truth is that there are a whole host of organic compounds, and their effects on fish are going to vary.

Bearing all this in mind, and the fact that "inches per gallon" is a very crude rule of thumb (more on that later), I sat down and assessed stocking in my main tank this morning. It was an interesting exercise - based on the "inch per gallon" rule, my tank is slightly overstocked. Of course, that involves weighing a 3.5-inch kuhli loach as placing a greater demand on the system than a 3-inch Macropodus (which probably has more than twice the body mass, but almost no dissolved oxygen demand). If I chose to follow the "two inches per gallon" rule, I could almost double the stock of fish in my tank. Right now, that seems reasonable - the upper two thirds of the tanke are currently occupied by three fish; everyone else is near the bottom of the tank (and largely hidden by the plants). Things looked different this morning just after I fed the fish - in the flurry of activity, the tank seemed to have twice as many fish as it does now.

Aside from the obvious issues of filtration and water changes, I think there are two main things to think about when it comes to stocking - the space available, and the overall ecology of the tank. The main tank tends to have higher nitrate levels than either of the small tanks. This is largely a function of the amount of plant biomass - the other tanks are choked with plants, which presumably consume any available nitrogen. The main tank, on the other hand, has far less plant biomass (though this may change). Increasing the plant biomass probably increases the overall number of fish the tank can support. The other issue is one of space. Where in the water column does a fish live? Recommendations for cory stocking seem to be expressed in terms of tank surface area - or actually, the area of the base of the tank. (Is this modified by having a more heterogeneous tank bottom?) In my main tank, the open water is only used by the Macropodus. The corys spend their time on the bottom of the tank, with occasional forays up and down the plants. The Glowlight tetras tend to swim among the plants, while the Rummynose like the open water in front of the plants - they rarely venture above the level of the taller plants. (I suspect that as the plants get taller, they will expand their usage). So in terms of fish to add, the obvious choice would be an open-water species (zebra danios are what come to mind) or a surface species (guppies or some other small live bearer?) That is, of course, if I decided to trust the two-inches-per-gallon rule of thumb...

Thursday, 14 August 2008

Tank talk and lighting options

As often happens, I went through a period of neglecting my tanks, especially my (55-gallon) main tank. It's the kind of thing that happens to almost every aquarist at some point in time. The main tank has always been light-deficient - while most people recommend 2-3 watts per gallon* for a planted tank, my plants were forced to get by with approximately 0.55 watts per gallon. As long as I was feeding them Flourish Excel, the plants seemed happy (especially the Cambomba), but once I quit, only the Java fern and Echinodorus ("Amazon swords") did much.

While the main tank was suffering a lack of plant growth (somewhat masked by the expanding Java ferns), my other tanks were experiencing the opposite problem - too much plant growth. The plant tank was covered by an emergent carpet of Ludwigia and Bacopa monnieri; the tank itself had turned into a mass of roots. The Otocinclus tank was similarly overgrown, although instead of being covered by emergents, it was covered by a think layer of floating plants.

At the end of July I shook myself out of my torpor and started moving plants from the plant tank to the main tank. I realised that I had to upgrade my lighting, but at that point in time, it just wasn't an option. I replanted a lot of Ludwigia and a little Bacopa into the main tank, and cleaned up the mass of floating vegetation (I either replanted the stuff, or got rid of it). And then I had to leave it all alone for a week and a half.

One of the main reasons I wanted to clean out the plant tank was the fact that we would be gone for a while. I don't have a timer on that tank, so I have just left the lights on when we are gone. One time I returned to find the tank a thick mass of hair algae - so thick, in fact, that the water was obviously not circulating (some areas were very warm, others were far too cold). While that is likely to be less of a problem in summer, I still wanted to clear out enough vegetation to give it some room to grow. But moving plants to the main tank created a problem - did I really want to go to all that effort, and then watch the plants turn into spindly things before slowly dying? While a lighting upgrade was in order, I had neither the time nor the money for anything of the sort.

On the way home from Michigan I finally stopped into Preuss Pets in Lansing, Michigan. A friend of mine has been saying great things about them for years, all the more now that they have moved to a larger place (more later). I ended up buying a really nice new lighting system, and I now have two 54 watt bulbs on the tank. Not too surprisingly, the change was remarkable. I have also continued to move plants from the plant tank to the main tank. It's too early to say home much of it will really take (a lot of what I transplanted was emergent in the old tank, so it will have to adapt to being submerged), but the tank looks great and the fish seem happy, poking around in the new vegetation.

* It's actually more complicated than simply "watts per gallon" - not only does the light output matter (not all 30-watt fluorescent bulbs are the same), it also matters what wavelengths the bulbs produce.

Wednesday, 7 May 2008

Baby Corys?

A while ago I tried to convince my pygmy corys to breed, but without much luck. Water changes (especially in coincidence with weather fronts) could get them to come out and "dance". Recently I have noticed more complex behaviour, including what looked a bit like the "classic-T" behaviour that spawning corys adopt. But I had pretty much given up hope of anything actually happening.

Last night I noticed something moving at the front of the tank. Before it darted back into the thicket of Hemianthis I saw something that looked like a tiny tadpole, maybe 4-5 mm long. It took me a moment to realise what I had seen - fry! Over the next couple hours I caught another glimpse of it. Very cool!

Now, I can't say for certain that it actually was a baby cory - there are also a few Otocinclus in the tank, but odds are that it was a pygmy cory. Pygmy corys are considered easy to breed, while Otos are rather less easy. Also both fish are easier to breed in groups - I had 7-10 corys in the tank, but only three Otos (and one, I suspect, is a different species from the other two).


While I have read some of the people at ScienceBlogs on a daily basis for months, I still have not plumbed the depths of what’s available in terms of good reading. I recently came across Shifting Baselines, a good ecology/conservation biology blog written by Jennifer Jacquet, a doctoral student at the University of British Columbia, Josh Donlan, a conservation scientist at Cornell and Randy Olson, the creator of A Flock of Dodos.

In January, Jacquet discussed a study which looked at replacing fishmeal (which is used to feed chickens, pigs and fish) with “bugmeal”. Working with striped bass, researchers at Mississippi State University found that the fish readily took the “bugmeal” and the final product was similar to fishmeal raised fish, but had a less “fishy” smell (which is considered a bonus by American consumers). Today she presented some response to questions she asked Lou D’Abramo, the lead scientist on the Mississippi State project.

The first question really gets to the heart of the problem of our industrial food production system: what are the insects raised on? The answer - grain, probably corn. Lovely. Fortunately, D’Abramo seems to be aware of the problem with that, and discussed the idea of raising them on fish wastes. He also talked about raising insects on waste products to alter their fatty acid profile - something that wouldn’t have have been the least bit surprising had I read that with my aquarist brain switched on…you read a lot about fatty acid profiles in the context of getting your Corydoras to breed. (I should do a less good job of compartmentalisation.)

Finding a substitute for fish meal is a good thing. Insects sound like a good substitute. But our industrial system of agriculture just makes things like this awfully complicated - needlessly complicated. Small farmers feeding fish on grubs or mealworms raised on locally generated waste sounds workable. Industrial-scale “bugmeal” production, on the other hand, raises the usual problems of energy demands, transport, and waste production. One step forward, but we’re on a conveyor belt running us backward…

Tuesday, 26 February 2008

Otocinclus notes

Otocinclus, the dwarf suckermouth catfish, is a very popular algae-eating catfish. The seventeen species of Otocinclus (often called Otos) are very popular for algae control. Unlike their large cousins, the Plecos, Otos remain small and are not boisterous enough to cause damage to plants. Although they are often purchased singly for algae control, Otos are social and should not be kept in groups of less than three. They are native to South America east of the Andes mountains, in streams that drain into the Amazon, Orinoco, Paraguay/Parana rivers, and in streams that drain into the Atlantic in southeastern Brazil. They are notably absent from the Guianas.

Otos are small - they range in size from 16.5 to 43.8 mm (0.6 to 1.7 inches), not counting the tail. Females are 10-20% larger than males, and have a broader body, especially when they are in breeding condition. [Read the rest of my post at]

Corydoras notes

With 150 formally described species, and perhaps more than a hundred undescribed species, the genus Corydoras offers great possibilities for fish keepers. All species are easy to keep, relatively undemanding fish with great personality. Many of them are readily bred. For the average fish keeper they are relegated to the "cleanup crew" and kept singly or in very small groups. Even under those conditions, they can be interesting fish. Kept in larger groups, they really shine and can become the focal point of a lively aquarium.

Corydoras are social fish - they should not be kept in groups of less than three. They appear to be happiest in groups of six or more. With the right selection of fish and appropriate aquascaping you can enjoy almost constant activity as they swim around a community tank. [Read the rest of my post at]

Snails in aquaria

Snails are nearly ubiquitous in freshwater aquaria. Aquarists vary in their attitude towards snails - many see them as a scourge that must be controlled, if not eliminated outright. Bulletin boards are full of questions about how to control snail populations. Snails are easily introduced on plants, rocks or other decorative items like driftwood. Most reproduce quickly and some, like Malaysian Trumpet Snails, quickly grow to the level of infestation. Some snails eat plants, and can damage aquarium plants. Some will eat eggs, even baby fish. And some play a role in the life cycle of fish pathogens.
Many aquarists seem snails in a more positive light. Snails consume algae and can keep glass and rocks clean. Snails consume dead plant parts and uneaten food that might otherwise decompose and foul the water. Trumpet snails burrow through the substrate and bring oxygen into these substrates.
Quite apart from this utilitarian view of snails, some aquarists see them as desirable pets, and may dedicate aquaria to certain species. Popular pets include Olive Nerita snails, Ramshorn snails and Apple snails (also known as Mystery snails). [Read the rest of my post at]

Pygmy corys

They say that pygmy corys (Corydoras pygmaeus) are easy to breed. That is, of course, a relative statement. "Easy" relative to what? But at this point, doing so is one of my primary goals.

In general, in order to breed corys you need frequent water changes coupled with a "conditioning" diet. They conditioning diet is a rich diet - often with a lot of live food, and essential fatty acids - that bring the fish into breeding condition. Water changes, on the other hand, mimic the beginning of the wet season, when streams and pools get an influx of fresh water. Fresh water, often cooler (although people have said that "cooler" is not important for pygmy corys).

The tank the corys are in is open-topped. As a result of this, evapouration rates are high. Over the last several months, this has meant that I am more inclined to add water than I am to exchange water. Presumably that resulted in very hard water - not the optimum for these fish. So over the past few weeks I concentrated on getting the water closer to tap water, but doing frequent, large water changes. Over the last week I have tried to soften the water some more by adding reverse osmosis water.

The pygmy corys have responded fairly well to the water changes - they seem much more active the past few days, although they still spend most of their time hidden below the dense lawn of Hemianthus. I'm cautiously optimistic.

Sunday, 24 February 2008

Otocinclus tank

It's been almost a month since I re-did the former Macropodus tank. After I cleaned the tank out and added some new plants, the old plants died back seriously. It was especially noticeable with the Echinodorus, which had previously dominated the tank. Their leaves first went pale, and then much of the tissue died, but not the whole leaf.

Apart from adding a lot more plants, I also created a small "sand lens" in the front of the tank. And, of course, I added a population of Otocinclus and two dwarf corys. So how have things changed?

Here's the tank today; while I'm having a hard time getting the Lilaeopsis to root, the Hemianthis is really coming along nicely.

Here's the tank three weeks ago, when the die-back had just started

And here's the tank three days before that, shortly after I had cleaned it out

Monday, 11 February 2008

Using biogeography to guess at species identity

Just over a week ago, I found two Corydoras habrosus mixed in with the Otocinclus at the local Petsmart. Since C. habrosus is restricted to the Amazon basin, it struck me as a useful clue in trying to identify the Otos. In his 1993 monograph on the genus Otocinclus, Scott Schaeffer mentions that only two species of Otocinclus are found in the Orinoco basin - O. vittatus and O. huaorani. I'm leaning a little more towards O. vittatus, but I really need to take a better look at them.

Friday, 8 February 2008

Shape or colour? It depends on where you grew up

Dave Munger at Cognitive Daily reports on a study of how the environment in which fish are raised affects their spatial perception and memory. Convict cichlids raised in square tanks used shape and colour to navigate, while ones raised in round tanks relied on colour more than shape.

Thursday, 7 February 2008

Diversity in Malawi cichlids

Ed Yong has an excellent discussion of the way in which male aggression contributes to species diversity in Lake Malawi cichlids. While a number of factors were involved in the rise of this species flock, the tendency for males to be more aggressive towards males that look like them is likely to be one of the factors that drives speciation.

Wednesday, 6 February 2008


Judging by the Google searches that bring them here, a lot of people who find there way here are looking for the answer to a specific question...answers that my posts often don't provide. If you have questions - feel free to ask. I can't make and promises, but I'll give you the best answer I can.

Sunday, 3 February 2008

Otocinclus tank

While many aquarists value Otocinclus catfish as algae eaters, they seems to be looked on more as a part of the tank maintenance system than as "pet fish". And quite frankly, my impression of them was that they just weren't the most exciting fish. While I found them interesting, they never seemed to do much. So I was intrigued by an article in the February issue of Tropical Fish Hobbyist by Gary MacDonald. Not only did he say that they are very social fish, he also spoke of interesting dominance hierarchies in groups of 12 or more. While this caught my attention, I didn't feel like I had room for another dozen or so fish in my main tank. With the former Macropodus tank available, I ended up buying some, pretty much on a whim.

From what I've read, one of the major concerns about pet store Otocinclus is that they are often starving - they are herbivores, and are likely not to have had enough to eat for a while. There is also the stress involved in being caught and transported home. Once I got them into their tank, they all went for the bottom or the sides of the tank and just suck there. But after a few hours they were extremely active, swimming all around the tank, presumably examining surfaces for algae. They have slowed down a little since then, but they remain much more active that any Otocinclus I have seen previously. Of course, they are also very young - I wouldn't be surprised is they slowed down a lot as they matured. It'll be interesting to see what happens.

The great cory hunt

After finding a pair of Corydoras habrosus at a local Petsmart, I saw this post at PlanetCatfish - the poster had received a C. habrosus in a group of Otocinclus, presumably in Missouri. That got me thinking - since all the local Petsmarts presumably get their fish from the same source, maybe there were more C. habrosus at other local Petsmarts. So we decided to go on a cory hunt. We visited four of the seven Petsmart stores in the Oklahoma City metro.

We failed to find any more C. habrosus, but it was fun to try.

Tank shots

In the past couple days I added more plants to the tank, trying to create something of a thought-out aquascape (or at least something that could be thought of as something like a thought-out aquascape. Here's how it looked three days agoI added Hemianthis, Lilaeopsis and some Vallisneria to the forground, and planted a number of stems of Cabomba along the back, in front of the heater. I also added some Ludwigia along the centre, to add some more dimension. This is the way it looks now

New fish

For no reason in particular, I visited our local Petsmart today, and was rewarded with a rare treat - in a tank of Otocinclus there were two dwarf corys - not pygmaeus, but I knew it must by one of the others. It turned out to be Corydoras habrosus, a Venezuelan species.

That pretty much decided the fate of the former Macropodus tank. I couldn't put the new corys into the main tank (they're a bit small to cohabitate with adult Macropodus), and I didn't want to add them to the plant tank without quarantining them first. So that left the former Macropodus tank. And since I didn't want to leave them as the sole occupants of the tank, I took the opportunity to buy a dozen Otocinclus, as Gary had recommended.

Thursday, 31 January 2008

New cyprinid genus

A new genus of cyprinids, Hongshuia was described in China recently to accommodate two new species, Hongshuia paoli and H. banmo, which have been described from the Pearl River system in Guangxi Province in South China.

Source: Practical Fishkeeping.

Display tank or breeder?

As I mentioned previously, I now have an available tank to stock. The first step was cleaning it up - the tank was badly overgrown and the substrate was very dirty. Over the course of cleaning it took 10 or 15 gallons of water out of a 10-gallon tank - and even then, I didn't get the substrate completely clean.I took out most of the Rotala - it just hadn't taken very well in that tank. I also pruned the Echinodorus plant rather severely - that should let more light through. I may need to add some more plants to the foreground, from the perspective of a "planted tank" it has a major deficiency - the lack of adequate substrate. The tank has nothing but rather garish red and black gravel. In the course of cleaning it up, I took most of the organic material out of the substrate, thus removing most of its nutrient-holding capability.Now I need to figure out what to do with this tank. Do I want to give the corys a chance to breed? Having done so much to make the tank pretty, do I really want to turn it into a breeder? Or to put it differently - can I make a breeding tank visually interesting? If I had a few more pandas I could make a little shoal of them...but the reason I want to breed pandas is my lack of pandas.

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.

Wednesday, 30 January 2008

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).

Sunday, 27 January 2008

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.

Saturday, 26 January 2008

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.

Thursday, 24 January 2008

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

Wednesday, 23 January 2008


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

Tuesday, 22 January 2008

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.

Monday, 21 January 2008


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.

Sunday, 20 January 2008

More cory pictures

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


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...

Saturday, 19 January 2008


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.
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.

Thursday, 17 January 2008

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.

Wednesday, 16 January 2008

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.

Tuesday, 15 January 2008

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.


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.

Monday, 14 January 2008

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.

Wednesday, 9 January 2008

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.

Tuesday, 8 January 2008

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.

Monday, 7 January 2008

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.

Sunday, 6 January 2008

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 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.

Friday, 4 January 2008


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.

Thursday, 3 January 2008

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.