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).

Hybrid corys?

While I've heard reports of putative Corydoras hybrids, I have never seen any direct evidence of interspecific mating until this past week.

My main tank has a variety of corys - Corydoras panda, C. punctatus, C. arcuatus, C. aeneus, a probable C. trilineatus and another species whose identity I don't know. While I started off with several C. trilineatus, I only have one left. And apparently it's a female.

A few days ago, in a rainy week, one day after doing a water change, I noticed the trilineatus in the t-position that corys adopt while mating - with a panda. She then swam off grasping at least one egg (probably more) between her ventral fins.

While they clearly mated, I have no idea if the eggs would have been fertile. Regardless, I would be very surprised to find any fry. When she tried to place an egg, the rummynoses realised what she was doing, and proceeded to chase her around, hoping for some more eggs, I presume. Even though I tried to distract them by feeding them, the odds of eggs remaining unfound in that tank are probably pretty slim

Kribs

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?

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).

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.

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.

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.

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.

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.

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.

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

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.

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.

Breeding Angelfish?

Two of my four angels died in the aftermath of my neon tetra fiasco. Since I lost one member of each "pair" of angels, I figured that my chances of breeding them was pretty close to nil. However, the two surviving angels are now behaving like they intend to breed.

Over the last week or so, the angels became very aggressive with one-another. That was nothing new - when there were four fish, they fought over the tank. One pair claimed the central half of the tank, and forced the other pair to occupy the ends of the tank. But this behaviour was different - one fish would attack, but the other would stand its ground, but not fight back. More tellingly, they have taken to cleaning Echinodorus leaves. After reading Bill Dawes FAQ on breeding angels, it seems pretty likely that they are attempting to spawn.

Life and death

...luckily, without life in death.

Only one of the neons survived the weekend, which is really sad. It may have been a water-quality thing, I'm really not sure. Yesterday was truly tragic - my fighter, an angel and one of the platies all died. I was worried about the angel - it had a large gash on its side on Thursday morning. I was saddened, but not shocked, that it had died. But I'm not sure what killed the other fish. I did a major water change, but I'm not sure what else I could have done. But to little avail - now a second one of my angels is dead. It's really sad - they had grown into such nice big fish. I really wonder if the neons didn't bring some disease - why don't I quarantine new fish? You'd think I would have learned my lesson.

And in terms of life, the plant tank is full of Macropodus fry. I was hoping if I didn't feed them they wouldn't make it, but that isn't the case - there seems to be enough in there for them to eat...protists feeding on a healthy growth of algae and bacteria, I suppose.

Macropodus fry

The Macropodus nest was in a difficult place to see easily, so it was hard to see if there were eggs, but after a few days I started seeing the fry. Today there are 30-40 fry (maybe more) on the glass below the nest. Now I have the great challenge - do I feed them? I don't want to - I have more Macropodus than I know what to do with. On the other hand, I don't feel comfortable with the idea of just letting them starve to death (letting them get eaten doesn't upset me, but letting them starve does, for whatever reason.

The other issue is algal growth. An awful lot of algae has grown along the glass in the tank - mostly along the right side (where the light is) especially along the back (which is against the window). I'm also getting algal growth (maybe cyanobacteria) along some of the gravel. On one hand, since my main interest is plant growth, this should not be a bad thing. On the other hand, the algae can overgrow the plants. One solution might be more plants, another is to get some more Otocinclus (since I only have one in the main tank, they could move over once they have acclimated and knocked the algae back a bit).

Macropodus: The Next Generation

To serve as a nitrogen source (and create some circulation in the plant tank), I added a few of the baby Macropodus from the breeding tank. A quick pass netted four fish - the largest one, a male, and three smaller ones that appear to have been females. Once he realised that he was the biggest male in the tank, the male Macropodus got to work nest-building and displaying at the females. On Saturday, after less than a week in the tank, he had a fairly large nest. Over the course of the evening he and the largest female have started mating. Although they are still rather small, they appear to be successfully producing eggs - perhaps 3-5 of them are visible floating around after most of their "rolls". While for rather obvious reasons I don't want any more Macropodus (I still have about 30 of them in the breeding tank), it's still pretty cool to see the fish you bred breed.

On a more focussed note, the plants seem to be growing quite well. The light intensity is high enough (at least on one end to the tank) to produce reddish foliage. There has also been noticeable growth over the last week. It really suggests that what I need most in the main tank is better lighting.

Fry update

There are quite a few Macropodus fry around - most of them are clinging to floating vegetation, but there are a few free-swimming individuals. That raises a question - are two-day-old fry going to be doing any swimming, or are these a mixture of newborns and 10-day-old fry? After I saw the male Macropodus eat most of the fry, I assumed that there were none left. While that still seems more probable to me, it's also possible that there were survivors of the original batch. I'd say "we'll see", but no, not really - the odds of many fry surviving in the community tank is pretty slim, and even if they do, the radically different growth rates that I saw among the first batch of fry make it impossible to connect size with age.

Empty nest?

Looks like the Macropodus nest is empty. I didn't see anything in there this morning. Linz mentioned that the male didn't seem to be doing a very good job of keeping the eggs in the nest either. Oddly, he still seems to be defending the nest.

Update: Turns out that I was wrong - there were actually quite a few fry in the nest. So will the male Macropodus eat the fry tomorrow? Should I leave the lights on tonight, so that he doesn't have to gather up so many fry (and end up "forgetting" to return them to the nest like last time), or should I switch the lights off and maybe give a few of the fry a chance to escape into the vegetation, which is now considerably more dense than it was last weekend (thanks to the plants I got from Bob)?

Update II: As of Monday morning, there are still quite a few fry around. Most of them have left the remnants of the nest and are on the underside of a large Echinodorus leaf that's floating on the surface of the tank. While the male Macropodus was still defending his portion of the tank, I couldn't tell if he was doing anything to "manage" the babies.