Corydoras, From Small beginings

Author: Ian Fuller

My first visit into the realms of catfish, or more precisely Corydoras, was way back in 1974. While out with a friend on a fish-buying foray, visiting several of the midlands best known aquatic shops. In one particular shop in Coventry (Alas no longer there), I came across a tank containing what were labeled 'Dwarf Corydoras' Corydoras hastatus, I later found out the correct name was Corydoras pygmaeus. There were about 50 in the tank and to me they looked fantastic, all swimming around in one large shoal.

After talking with the shop owner for a while I decided that the little catfish would be a must for the living room tank and duly bought two pair. It wasn't until we were well on our way back home that it dawned on me, the tank that these catfish were to be housed in was not suitable in its present state and needed to be stripped down and re-set-up. The main problem was where to put the catfish in the meantime, the shop owner had told me that these fish were very hardy and tolerant of temperature fluctuation, he said the lower end of the tropical range (70ºF - 75ºF) would be ideal for them. With this in mind when I arrived home I immediately started acclimatising them to our local water, by putting them with the water they came in into a four-inch show jar, these were very popular at the time for displaying fish in at open shows. Over a period of an hour of so, making small water changes at a time, I completely changed the water in the jar for water from the tank. The little catfish seemed totally unperturbed by all the activity, in fact seemed quite excited every time new water was poured in, actively swimming up into the incoming flow.

The room temperature felt quite warm, so I thought it would be safe enough to keep the little catfish in the jar on top of the fireplace until the main tank was ready. I put a thermometer in the jar in order to keep an eye on the temperature, which settled at 68ºF. Later in the evening when the fish had settled, I gave them a little food in the form of crushed flake, which I am pleased to say they took to straight away. Unfortunately the jar was going to be their home for at least three if not four days, to allow me to sort out the main tank and let it settle for a couple of days.

On inspection the following morning, there was quite a lot of debris on the bottom of the jar, this was siphoned of using some air line and the water topped up, but this time I had to use the relatively fresh tap water from the now freshly set-up main tank. A little later in the day the little catfish seemed to be in some kind of distress, or so I thought, because they were all actively chasing each other around the jar, then after a while they settled down again and started searching around the bottom for particles of food. The next day was a work day, so it was a quick siphon, top up and then of to work. Later that evening after returning from work I went to give the little catfish some food, only to find what I thought were oxygen bubbles on the inside of the jar, there were about 100 of them altogether all confined to the corners. I sat watching them for a few minutes deciding what to do, thinking that there was something wrong with the water. The fish themselves seemed happy enough and were busy with their own little games, while watching I saw one of the two larger fish pushing itself head first into the side of a smaller one, then both fish started quivering, a few seconds later they separated. It was then I realized that the bubbles were in fact eggs and I had just witnessed my first Corydoras spawning. I continued to watch until all the mating activity ended and was then faced with another problem, what to do next! Put the catfish into the main tank, which I felt, was not mature enough, or to put them into another four inch show jar. After a little thought I decided that as the water they had spawned in was the same as that in the main tank there should not be a problem, so the four fish were gently tipped into their new home and the jar topped up again from the main tank.

I took a feed line from the main tanks air supply and added an air stone to keep the water in the jar moving and fully aerated. After two days all the eggs started to darken and by the end of the fourth day all of them had hatched, the tiny fry with their large yoke sacks could be seen quivering on the bottom of the jar, where they remained for two days. On the sixth day after the spawning took place all the fry were free swimming and scurrying around the jar. The fry seem quite large considering the size of the eggs they emerged from. In anticipation I had bought some powdered fry food as well as obtained a microworm culture from a friend and it was small amounts of this that the babies were first fed on. Growth was fairly slow to start with, at one week they were 4 millimetres in body length but by the time they were three months old they had reached 18 millimetres. There staple diet throughout was fine pre-soaked flake, with supplementary feedings of microworm or newly hatched brine shrimp.

Their growing on accommodation was also changed, a 10 x 8 x 6 all glass tank was made, which contained a thin layer of smooth sand on the bottom and a sponge filter to help keep the water clean and aerated. One of the most striking features about these little catfishes is the colour pattern changes they go through on their way to reaching maturity. I decided at that point that it might be a good idea to keep a record, whether it in the form of notes, sketches or photographs, of everything that I was fortunate enough to breed. I even record the details of the failures because I think we probably learn more from failures than from successes.

Corydoras pygmaeus have a lot going for them. They are small at 25 mm for males and 32 mm for females, very peaceful, always active, will eat just about anything offered providing its not to large and most importantly they are reasonably cheap to buy. You don't need large tanks to keep them, I would say that they are perhaps the easiest of all the Corydoras species to breed and raise. If they are given a reasonable amount of room, an 18˝x 10˝x 10˝ (45cm x 25cm x 25cm) would house six pair comfortably, plenty of cover, I use Java moss for this purpose, and are well fed, they can be successfully kept and bred without the need to separate the adults from their eggs after spawning.

Article reproduced by kind permission of Ian Fuller of www.corycats.com

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