Corydoras in the Garden Pond

A friend bought me a school of Corydoras palaeatus because she thought they were cute (which they are). But they aren’t the best companions for pufferfish, which seem to make a bee-line for their dorsal fins whenever said pufferfish is feeling a little hungry. So over the summer, I put them outside in a simple garden pond filled with lots of plants but no filter. The pond itself is filled with animal and plant life of all kinds, including on occasion, frogs. Actually, calling it a pond is overusing the title a bit, as the pond is nothing more than a plastic mock half-barrel that holds around twenty or thirty gallons of water. Even so, it has its own ecological balance, and provides me with a good supply of live foods, such as snails and daphnia.

Once the weather started too cool down, I brought the Corydoras back indoors and put them into the 180-litre tank. Almost at once they began spawning! I tried to move the eggs to a breeding trap, but in the process squished most of them and the rest went fungussy. So I moved the Corydoras to a smaller tank in which I was breeding some Dermogenys halfbeaks. Early one morning the catfish began to spawn again.

This time I let the eggs sit for a few days and harden up, and in the meantime removed the Corydoras to a another tank alongside some cardinal tetras. The halfbeaks had also produced a litter of four healthy fry, so the adult halfbeaks were taken back to the community tank. About five days later I noticed the eggs were beginning to hatch, so I gathered up the unhatched eggs quickly, by carefully rolling them with my fingertips and into a breeding trap. Fry that had already emerged were sucked up using a pipette.

I seem to have about fifteen Corydoras ‘kittens’. One reason I didn’t have more was that the snails in the tank seemed to have eaten some of the eggs. This breeding tank is filled with halfbeak-friendly food items such as daphnia taken from the pond, and sometimes snails come in as well. These are no threat to the halfbeaks, and I actually let the snails multiply because they are useful food for pufferfish. But it’s obvious that snails aren’t so friendly to catfish eggs.

A day after hatching I started to place food in the breeding net, primarily Liquifry but also small amounts of green thread algae taken from the pond. I’m assuming this stuff is filled with infusoria and other tiny morsels of food. There’s probably plenty more stuff for the kittens to eat in the aquarium, which has been topped up with pond foods for several weeks while I was conditioning the halfbeaks. But I’m worried the kittens are still so small and could be eaten by something like a snail or planarian.

The kittens are growing quickly, and within three days already had the characteristic peppered markings of their parents. I’m still not sure whether they’re eating the Liquifry and flake food I put in the tank, or the algae and tiny pond animals already in there. There are fifteen fry in the net, and at least two more swimming about in the tank among all the other little creatures. I’m going to leave those where they are, as they seem to be doing perfectly well.

By six days of age, the kittens are surprsingly well developed, with a nice set of barbels to help them find their food. So far, they seem to be taking mostly algae and detritus, but I’ve been adding Hikari “First Bites” baby fish food as well. In terms of behaviour, there’s no schooling yet, and the fry that are loose in the aquarium mostly alternate between hiding underneath things or scooting about foraging.

After about a week from hatching the little kittens had easily doubled in size and were also much more bulky than before. Their pectoral fin spines seem to be developed before the dorsal fin spine, and when swimming, their pectoral fins are very obvious. Mostly they swim around the bottom, and there’s no sign of the typical adult Corydoras dash to surface for a gulp of air.At nine days of age, I let the remaining Corydoras in the breeding trap loose. They seem large enough, and more importantly active enough, to be safe from any possible threat from snails or planarians. It’s astonishing how quickly they are growing. Instead of being mere scraps of life, they really do look like little catfish. But they are still very small: note the daphnia swimming above the head of the kitten photographed below. Nonetheless, they are managing to eat catfish pellets perfectly well.

I did lose two or three babies during the third week post-hatching, most probably through under-feeding. These baby fish are eating a good deal more food that I’d imagined! The key seems to be putting in small amounts of catfish pellets every few hours. Into the fourth week, the baby catfish are robust, well-developed little fishes. Though not easy to count, I seem to have fifteen fish. Most are about the same size, but at least a couple are pretty small relative to their siblings. Just like their parents, these catfish are very sociable, as this picture below demonstrates.

Rana temporaria visiting my garden pond

Corydoras paleatus eggs

Corydoras paleatus hatchling, one day old

Corydoras paleatus about nine days old

Corydoras paleatus about seven weeks old