Wednesday, 15 October 2014

Blackworms

I've never given my fish live food (other than brine shrimp and some inverts that somehow colonised one of my tanks) but I got my hands on a bunch of blackworms that were left over from a lab exercise. So into my tank they went and the massacre commenced.

Blackworm behaviour is interesting - in a smooth container they form a large mass of worms which coil together. When I dropped them into my tank they initially clumped together - the ones that landed on plant stems turned into a mass the reminds of a group of swarming bees which have settled on a tree trunk.
Cluster of blackworms on a Ludwigia stem. 
Once the blackworms made it to the bottom of the tank, their behaviour changed. Instead of remaining in a tight clump they spread out on the bottom of the tank with one end buried in the substrate and the other extending into the water column



In normal circumstances, this is probably a good way for the blackworms to forage while providing themselves with an escape option. From the Wikipedia article about Lumbriculus vaiegatus;
When touched, L. variegatus will attempt to escape, either by swimming in a helical ("cork-screw") fashion, or by reversing its body. The escape pattern used depends on where the worm is touched: anterior touch elicits body reversal, whereas posterior touch triggers helical swimming. L. variegatus has quick reflexes, and uses its photoreceptors to detect shadows and movement, both used to escape threats. The posterior end lifts out of the water and forms a right angle. It is then exposed to air and is used to exchange oxygen and carbon dioxide, although this exposes its posterior to its enemies. If the photoreceptors detect a shadow or movement, the posterior rapidly shortens in response to a threat.
Given the way that the blackworms positioned themselves on the bottom of the tank, it seems likely that the reversal behaviour draws the organism down into the substrate where it would be safe from predators.

Absent the corys and kuhli loaches, the blackworms which made it to the bottom of my tank would probably have been safe. While the tetras greedily attacked any floating worms (and eventually found the worms that had settled on the vegetation) the worms that made it to the bottom of the tank seems to have been safe from them. Even the large mass of worms in the second picture (above) elicited no response from the tetras (although they were eventually find the worms which had settled on the vegetation. The corys, on the other hand, were not only able to find the worms on the bottom of the tank, they also seemed to be quite successful at digging them out of the gravel (and in so doing, managed to uproot several plants). A day later there were still a few worms sticking out of the gravel where the thickest clump had been located, but I don't see any left. It's entirely likely that some - maybe even many - survived by burrowing into the substrate where they can grow and reproduce (and hopefully, continue to become cory food). But that might just be wishful thinking,

Saturday, 20 September 2014

Managing algae III

Things quickly went from bad to worse.

I coupled a water change with manual removal of a large amount of various kinds of algae. I dug through my collection of 'aquarium stuff' and found an (old) bottle of Seachem Flourish. Great; although it's not marketed as an algaecide, it often works. So I added some. Then I realised that what I had wasn't Flourish Excel, and rather than adding a carbon source, I was adding fertiliser. Not what I was thinking, but it should still boost plant growth, and hopefully would help them compete with the algae.

Already on Friday (the day I did the water change) I noticed that they water wasn't terribly clear; by Saturday it was noticeably more cloudy. The algae on the driftwood was also growing like crazy, and I removed a lot more of it. Saturday evening I visited the pet store in search of Flourish Excel and found instead API CO2 Boost. Since it's basically the same stuff (glutaraldehyde) I decided to buy a bottle and see how it would work. I added my first dose that night.

By Sunday, it was obvious that something was wrong. I had a growing green water problem (overgrown of unicellular green algae). Over the next few days I kept dosing with the CO2 Boost, and the water kept getting greener and greener.




By Tuesday afternoon the water was very green and cloudy.

On Thursday it was bad enough that I decided to stop the experiment and do a major water change.


Wednesday, 11:40 am
Wednesday, 4:14 pm
Thursday, 11:58 am
As I started to refill the tank I added dechlorinator to the water I was about to add, together with the  CO2 Boost and, without thinking, the fertiliser. Then it occurred to me to wonder what was in it. A quick glance at the bottle clued me in to the likely cause of my green water problem - the first listed nutrients were N and P. Just what you don't want in a tank with a green water problem. At that point I realised I had a problem.



After the water change, things looked a lot better, but the water was still green (upper image). Less than an hour later, the water was noticeably greener.



Normally, the best course of action is to fix the problems with the water, but in this case it didn't seem like the most viable solution. I had elevated the levels of phosphate. It would probably have taken several water changes to get it back to something like the baseline level.I decided, instead, to dig out UV Steriliser. A UV steriliser uses ultraviolet light to kill microorganisms in the water. I bought it many years ago to fight ich (quite successfully) and hadn't used it in years.



Within a few hours, there was a visible improvement in clarity.
Two hours later, further change was visible.

The following afternoon, things have improved even more.

Afternoon of day two, and the water clarity is better than it even was.

By the morning of the second day (Saturday) the water was pretty much clear. Saturday afternoon, 48 hours after I started running the UV steriliser, and the water clarity is as good as it have ever been in this tank. I'm really impressed with how quickly it managed to get the job done. Granted, a 24 W unit is overpowered for a 55 gallon tank. But it did the job remarkably quickly.

Friday, 19 September 2014

Ghost shrimp

The latest addition to my tank is a small group of Ghost shrimp (Palaemonetes sp.). I like the idea of having shrimp in my community tanks, and Ghost shrimp are both large enough to coexist with the fish I have, and cheap enough that I can afford to keep them in conditions where successful recruitment of offspring is unlikely.

Fish are most interesting if they're are active swimmers. The appeal of shrimp, on the other hand, lies in the fact that they don't move much. They tend to spend much of their time in one spot, feeding on whatever detritus or algae is at hand. Being translucent, Ghost shrimp may not be the ideal aquarium shrimp, but they make up for this limitation by being cheap enough to stock at relatively high densities. They also happen to be large enough to coexist with the fish I have in my community tank - Glowlight tetras, imperfectly identified Blood tetras, two species of Corydoras, some Otocinclus and several kuhli loaches.

I decided to use my algae issues as an excuse to add a few Ghost shrimp to my tank. After all, there tends to be a relationship between species diversity and stability in ecological systems. I can't say it helped (I would honestly be very surprised if eight shrimp - or fewer - could make any change in a 55-gallon aquarium, especially given less than a week to work at it). Not to mention that they are supposed to feed primarily on algae.

After a week there are between five and seven survivors. I found one shrimp dead the morning after I purchased them (the smallest of the group); I'm hoping the rest of them made it. I saw five of them together yesterday - that sets the lower limit on the number of survivors - but generally I only see two or three of them at a time.
Palaemonetes paludosus, the eastern Grass Shrimp.
Public domain image. Original image by Joseph Stansbury Rosin, cropped and sharpened by Kazvorpal.
The Ghost shrimp available in pet stores in the US appears to be Palaemontest paludosus, the eastern or riverine Grass shrimp. One of the most interesting things about these shrimp are that they apparently dig quite extensive burrows. Via The Aquarium Wiki
The Ghost Shrimp burrows to feed and digs its two to three foot deep burrow with the claws of the first and second legs. It uses these legs to draw the sandy mud backward and collect it in a receptacle formed by another pair of legs. When the receptacle is full, the shrimp crawls backward, reverses itself in a special turn around chamber and then deposits its load outside. The burrows are not permanent. A number of branches and turnaround chambers are found in the burrows and they have at least two openings to the surface. The shrimp use their pleopods to produce some circulation of sea water through the burrows. The pencil-sized openings of the burrows are typically in the middle of little piles of sand or sand with small pebbles.
This would suggest that tanks with coarse gravel bottoms may not be ideal for keeping these shrimp. It might also explain why I rarely see more than one or two of them at a time. It does seem hard for me to envision how such a small shrimp would build and maintain such an extensive system of burrows.

Female carrying eggs. Public domain image courtesy Vlad at The Aquarium Wiki.

Monday, 15 September 2014

Observations on Blood tetra behaviour II

Some further observation on the Blood tetras.

[Update: These may not be Serpae tetras, so I'm referring to them by the broader term, 'Blood tetras']

One of the obvious questions about these interactions between the "Serpaes" is the question of what's aggression and what's mating behaviour. Several days ago I noticed a few of them and a few Glowlights hanging around the top of my (small) clump of Cambomba. From what I have read of breeding Serpaes, it seems that fine-leaved plants (like Cabomba, presumably) are attractive sites for Serpaes to spawn (and presumably other Blood tetras). It makes me wonder whether these fish were feasting on freshly laid eggs (though, of course, if they were, it might have been Glowlight eggs as well).

Sunday, 14 September 2014

Serpae tetra? Or not?

One of the things I noticed about my Serpae tetras (or 'Red minor tetras' as they were labelled in the pet store) was that only one of them had the characteristic black 'comma' mark behind the operculum (i.e., the gills). That one individual was also significantly redder than the other fish.

I visited the same store today and noticed that in addition to their 'Red minor tetras' they also had a tank of 'White-finned rosy tetras' (Hyphessobrycon bentosi), and that these fish matched what I had. So, I wondered, were my original fish mislabelled? And what were these fish?

First problem was that name: white-finned rosy tetras. Google around and you find 'Rosy tetras' (Hyphessobrycon rosaceus) which look a fair bit like these fish, and 'Ornate tetras' (Hyphessobrycon bentosi). So do I give Petsmart the benefit of the doubt and trust their ID of H. bentosi (though it's noteworthy that their website, unlike the store, doesn't appear to attach a species name at all to the 'White-finned rosy tetras') or should I follow the more common result on Google and assume that they're H. rosaceus?

Unsure how to proceed, I decided to get a sense of the genus Hyphessobrycon. The Wikipedia article on the genus notes that there are over 100 species (as of 2005), but only a handful of these have Wikipedia articles. That said, the coverage of commonly kept aquarium fish is pretty decent, so I decided to see how well I could match my fish with those covered.

Some of them were easy to dismiss as candidate species. Hyphessobrycon columbianus, the Colombian tetra, is described as being silver-grey in colour with a turquoise tinge from the lateral line upward. Several others were also easy to dismiss: H. herbertaxelrodi (the Black neon tetra), H. heterorhabdus (the [Belgian] Flag tetra), H. megalopterus (the Black phantom tetra) H. anisitsi (the Buenos Aires tetra) and H. pulchripinnis (the Lemon tetra) are all easy to rule out; they look nothing like these fish. But that still leaves quite a few candidates (among the species with Wikipedia articles) that required closer examination.
The Black neon tetra, H. herbertaxelrodi, is clearly distinct in both colour and body shape from these tetras.
Photo copyright Juan R. Lascorz, licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
Ruling these species out was the easy part. Identifying a good candidate among the remaining species was a little more difficult. Hyphessobrycon amandae (the Ember tetra) appears to have a narrower body and smaller fins. The Flame tetra (Hyphessobrycon flammeus) has the right body shape, but has a pair of vertical bars. My fish also lack the prominent red spot associated with the Bleeding heart tetra (H. erythrostigma). This left five reasonable candidates: H. bentosi, H. eques, H. minor, H. rosaceus and H. sweglesi. These five deserved more careful examination.

My fish (Hyphessobrycon sp.)

My fish are orange-red tetras with a relatively thick body. The dorsal fins are back with white edging; the forward third of the dorsal fins are also white or red. Only one of them has the red 'comma' mark typical of Serpae tetras (though apparently not invariably present.
Note the black dorsal fin edged with white. The front end of the dorsal fin can also be white or red. The anal fins are also white-edged, with a black dot at the rear edge (not visible here). Also not visible are the white edges on the pelvic fins.
Same group of fish. Note the black spot at the distal end of the anal fin (clearly visible in the top fish).
Hyphessobrycon eques (Serpae tetra)

This was, after all, my first guess. The best argument against my fish being Serpaes is the fact that one of them clearly is, and he looks different from everyone else.
The black line behind the gills is clearly visible, as is the more intense red. Photo courtesy MiguelCampos, released into the public domain.

Hyphessobrycon minor (Minor tetra)

Given that these fish were labelled 'Red minor tetras' in the pet store, you'd think that 'Minor tetras' would be a very good guess for the identity of these fish. The problem is that this week, in addition to the 'White-finned rosy tetras' they also had a tank of 'Red minor tetras'. And in fact, these appeared to be Serpaes. That said, of course, assuming that the following image is correctly identified, it would be easy to confuse the two.
Copyright Yuriy Kvach, licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
Finding anything about these fish via Google is nearly impossible, since searches for 'Minor tetra' is going to be subsumed into searches for 'Red minor tetra'. The main distinguishing factor I can find is size, and since these fish are not fully grown, it isn't the most helpful.

Hyphessobrycon sweglesi (Red phantom tetra)

Another fish that looks very like a Serpae tetra, but this time with an even bigger spot behind the gills.
Courtesy Tsunamicarlos; released into the public domain.


Hyphessobrycon bentosi (Ornate tetra)

The tank I saw today at Petsmart was labelled 'White-finned rosy tetras' (Hyphessobrycon bentosi). They looked a lot like the fish I bought, but that doesn't mean they are the same.
Hyphessobrycon bentosi, Copyright Euripides, licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.

Copyright H. Krisp, licensed under the Creative Commons Attribution 3.0 Unported license.
Assuming that these pictures are correctly identified, the most notable difference (other than the body colour, which can wash out in stressed fish) is the lack of a black spot at the far end of the anal fin. Animal-World has the following to say about distinguishing these tetras from H. rosaceus (the Rosy tetra).
These two tetras are so similar in appearance that this fish is commonly known as the False Rosy Tetra. Both have a pink to deep salmon colored body, though this species is a bit more transparent. They also each have darker red markings on their fins. They differ in that the Ornate Tetra always has white tipped fins while the Rosy may or may not, and the Rosy has a black marking or 'flag' on its dorsal fin. Other common names this tetra is known by include White Tip Tetra, White Fin Ornate Tetra, and Bentos Tetra.
Not entirely useful, but it does suggest that the paler colour of these fish may not be incidental.

Hyphessobrycon rosaceus (Rosy tetra)

This brings us to our final candidate, the Rosy tetra. After all, the fish today were labelled as 'White-finned rosy tetras'.
Copyright Aquakeeper14, licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
Problems begin with the descriptions of the species. From Wikipedia
The rosy tetra has a light pink-white body with red fins, except the dorsal fin which can be black or white, and the caudal fin which is pink-white with two elliptical red spots on it. It has a faint black line from the top of its eyeball through the pupil, to the bottom of the eyeball. 
Animal-World has this to add
The Rosy Tetra Hyphessobrycon rosaceus is a fun addition to a peaceful community aquarium with other smaller fishes. It has the deep bodied shape of the larger tetras like the Bleeding Heart Tetra. It is also quite pretty with its deep salmon body color highlighted with red accents and bright white tips on the fins. 

Conclusions?

So what do I have? I don't know. Only the Serpae tetras and the Minor tetras had the black spot on their anal fin in any of the pictures, but sadly none of the species descriptions matched them at all. All I know right now is that I have some sort of Blood tetras. Beyond that, I'm still uncertain.

Saturday, 13 September 2014

Observations on Serpae tetra behaviour

As I mentioned previously, I recently acquired a school of Serpae tetras. And they weren't quite what I expected (though the fault was mine for not doing better research). So a couple weeks on, what do I think of them?

[Update: These may not be Serpae tetras.]

To their credit, they're attractive, active fish. They use the entire water column (at least with the tank-mates they currently have) but seem to favour the front of the tank. (Again, that might be specific to these fish, but they certainly are aware of humans and know that we're a source of food).

They are strongly motivated by food. My Glowlight tetras have limited interest in a block of dried tubifex (they will eat the floaters dislodged by other fish, but they won't attack the block itself) and almost none in algae wafers. The Serpaes, on the other hand, will greedily attack dried tubifex and sinking algae wafers. While the Glowlights will spit out flakes that are too large for them, the Serpaes hold onto any food and eventually swallow down whatever they get a grasp on (often looking like they're at risk of choking on the food, though I suppose that in order to choke you need lungs).

As tetras go, they're fairly aggressive. While most of the aggression is directed at conspecifics, they Serpaes seem to have effectively banished both the Corys and the Glowlights from their preferred terrain (the front of the tank) except when food is present, when they seem to focus their aggression on conspecifics. The intraspecific aggression is interesting - one fish will go at another with its dorsal and anal fins expanded. Sometimes the fish that's attacked will swim off (in which case the aggressor seems to give chase) while other times they will spin around and stand their ground, responding with a similar display. The two combatants may clash a couple times before one retreats, though rarely very far. This sort of thing usually happens around food, especially algae wafers.

Tubifex blocks are very light, very low density - they're just freeze-dried worms compressed into a block. Once they fish start to attack them, they are quickly dismembered (especially if the fish in question are Serpaes or Kuhli loaches...Corys, which don't actually bite into things, can't break the block up as quickly). Once the Serpaes get to them, they don't last very long. Algae wafers, on the other hand, as fairly solid, although they gradually soften up as they soak in water. Since they last longer, they are soon covered with a scrum of Corys which completely cover the block and only offer armoured tails to the Serpaes. As a result, the Serpaes gather around above the wafer, waiting for the wafer to be exposed (which happens every now and then as the Corys move the wafer around and flip it over, and every so often seem to lose the wafer entirely). It is at this time, when the Serpaes are gathered together for a prolonged period, without clear access to the food, that I observe most aggression.

I hope that as the plants grow the sight-lines in the aquarium will be more broken up and life will become more peaceful.

Friday, 12 September 2014

Managing algae II

The following combination is a great recipe for an algae outbreak: a relatively new tank, fairly high fish stocking, new lights and a long photoperiod. And that would be where I find myself.

My driftwood has always supported a large population of Cladophora. It had vanished while the log was dry, and didn't show up in the new aquarium until I replaced the lighting. I'm not sure whether this reflects a lag time in growth (from spores or resistant bits) or whether it was simply a response to the higher light. (Obviously the high light helped it grow, and grow it did, like crazy). While many aquarists consider Cladophora to be the bane of their existence, I'm actually fond of it, as long as it stays on that piece of wood. It does require regular removal, but given its coarse texture, it is actually quite easy to remove.

If Cladophora had been the only issue, I wouldn't have been bothered. I also managed to attract a population of what some call 'green dust algae' - fine stuff that covered the glass. Initially I took it for green water (which is a problem) but then I realised it was just on the glass. It's easy to scrape, but right now it's growing like crazy. My problem is that I also have at least two other types of algae, and these are a bit problematic. I have some blue-green algae forming in a couple places. I don't care about it on rocks, but it is also growing on my plants. That's a problem, that I will need to sort out one way or another (it's not an easy problem to solve). Then I have something that's new to me. It fits the description of 'green hair algae' (and possibly some 'thread algae' on my filter outflow). Not good stuff to have around. For starters, it seems to grow like crazy and attach to anything (plants, heater; it's even smothering the Cladophora). It's also very slimy and insubstantial - people recommend twisting it around a toothbrush to remove it).