Breeding Corydoras Catfish By Jim Atkinson

 

I have used the method described by Frank, i.e. lowering the temperature and then raising it again, and with the Bronze Catfish (Corydoras aenus) this worked fairly well. I might add that watching these fish spawn is absolutely fascinating – much more interesting than any other fish I have spawned. All the fish (I used 2 pairs at a time) go berserk and dash around the tank for ages, only pausing to produce another egg or batch of eggs. This may go on for hours at a time.

 

Perhaps I should start at the beginning. The first cats I decided to spawn were aenus - the bronze. I had 2 large females (about 3 years old and about 6 cm long) and two smaller and younger males. The fish are easy to sex - the females are much stockier than the males and when full of eggs look like they have swallowed a marble. The males are sleek and very much slimmer. The males often have a taller dorsal fin as well (particularly in the Peppered Catfish Corydoras paleatus).

 

All the fish had been kept in a community tank and the only real concession I made to them was avoiding a lot of salt (I still add 1 teaspoonful per gallon in their water), feeding tablets or pellets that would sink to the bottom or slightly overfeeding the other fish in the tank, as the Catfish were really bought as scavengers. When I decided to move the tank to another location I took the opportunity to catch the Bronze Catfish and put them in a different tank. Anyone who has tried to catch a big Catfish in a well planted community tank will realise why I hadn't really tried to catch them before.

 

So they were put into a bare tank until I could set up a breeding tank. However the new water and the slight change of temperature combined to induce the fish to spawn within a couple of days (and before I had got around to setting up the planned breeding tank). I set up another tank with gravel, undergravel filter, and aged water and transferred the fish to the new tank. They spawned again a week later. I counted about 300 eggs all together (in both tanks). The Bronze Catfish lay large clutches of eggs at a time - 20 or 30 is quite common. These are stuck in clumps all over the place. A lot of eggs are not fertile and cloud over and fungus within a couple of days. I assume this is why they are so well scattered, as one bad egg in a bunch can infect those nearby. In the first tank I left the eggs as they were and lost most of them (the tank was not filtered so I lost a lot of the fry). In the second tank I removed all the cloudy eggs as soon as I spotted them and the success rate was much higher. I raised about 100 to saleable size. They were fed on the usual mix of live foods as often as possible. Water conditions don't seem to be that important - I used half old (from the community tank) and half new (aged) water. Hardness was about 6-10 degrees DH, pH 6.8-7, and temperature 72-76 degrees F. I put a handful of shell grit into the growing tank - supposed to help in the bone formation in the growing fry.

 

To spawn other species (C. paleatus, C. metae, C. hastatus) I use a slightly different method. A tank was set up with gravel, undergravel filter, a heater, and water partly from a community tank and partly new. The fish to be spawned (all I had - 2 to 8 of a species) were introduced and fed the best food that I had - mainly worms such as white worms and Tubifex (live). If the fish are mature they will start to spawn within a week. I don't bother to lower the temperature or change any water (the tanks are fairly large and only contain a few fish). The Peppered Catfish produce a cluster of from 2 to 5 eggs while the metae and hastatus produce single or pairs of eggs. Again they are stuck all over the tank (which also contains several large rocks and an Indonesian Fern). The tanks don't have lights on them so the plant selected has to be a low light preference type. The fish often deposit eggs on the plant. Eggs are produced once a week - 20 to 30 at a time. To prevent the parents from eating them I transfer all good eggs to a small net-type fry trap within the breeding tank. The eggs, which are quite sticky, can be carefully removed from the glass etc. and dropped into the net trap where they take 4 to 5 days to hatch at 72 to 74 degrees F. Feeding on Microworms and newly hatched brine shrimp can begin after another 3 to 4 days. I leave a piece of the plant in the trap as the fry are very timid and need a bit of security. As long as the parents get really good food they seem to go on spawning weekly for as long as I want.

 

Corydoras hastatus don't eat the eggs or fry so they are left in the same tank all the time.

 

Editor's Note: Corydoras pygmaeus (another dwarf species) can also be trusted with their fry. Ours lived in a 30 cm cube full of Java Moss and there always seemed to be fry in the tank. For any of our newer members looking for a deeper involvement in the hobby, they could do worse than specialize in the Corydoradinae (Corydoras and relatives). For more Information ace "A Complete Introduction to Corydoras and Related Catfish" by Dr Warren E. Burgess (TFH 1987), which is in the club library. We used to have a few specialist Catfish breeders in the Society, but now it is a rare night that two species are up for auction in a single night.