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These are three of the "dwarf" Corydoras, so called dwarf as the average size for this fish is around 3 cms, the females being slightly larger than the males. The reports are separated by a few years, but will give a bit of guidance to anyone thinking of trying one of these interesting Corys C. pygmaeus My first dwarf Cory was C. pygmaeus, obviously not chosen because it's an eye-catcher, but simply to try a new species. I put a group of 6 fish in a 24" planted tank with no other fish.  Eventually the females plumped up and following a period of intense activity I saw the "T-position" quite a few times. The following day I could see eggs on the Java Fern, in the Java Moss and on the Ambulia but quite a surprise to see only 4 on the glass. Unlike my present approach, I removed the adults and left the eggs to hatch in a tank with decent current moving the water around. At one end I put a large shallow, weighted plastic lid where, with the flow switched off, I could see fry gradually appearing for microworm and powdered flake. At 2 months old they were just over 1 cm and feeding on flake and chopped up frozen Bloodworm. When they were grown on, I had 27 fish from this one spawn without any major problems. C. hastatus My next dwarf Cory was C. hastatus and I went into the venture expecting a similar result as with pygmaeus. They are a more attractive fish than pygmaeus and have a certain appeal in the way that they swim in mid water. I got a group of 6 fish at auction and for the first few months saw no activity until I noticed that the eyes of two females had become all black. I had read that this was a sign of spawning activity. Over the next week or so, despite careful observation, I saw no sign of eggs. A few weeks later and I saw a small fry dart under the bogwood! Gradually the number of fry I spotted increased to seven and it was at this point that I realised that they had probably spawned inside the hollow of my horizontal bogwood. (Apparently a popular site for these Corys). How many eggs they had laid I would never know. I later had more spawnings in small numbers but, compared with C. pygmaeus, it is a very slow process to grow on the tiny fry.  C. habrosus Having spawned Corydoras pygmaeus in good numbers, without too much effort, I thought that buying 5 C. habrosus would soon give me similar results. How wrong could I be! Over a period of 2 years in a well planted tank, I had seen a few pre-spawning "charges", but no visible eggs and never a single fry. This, despite regular water changes and using the stimulant of cooler water. There were small livebearers with them but the same set up did give me many fry from Cory oiapoquensis;- many from eggs artificially hatched and a good number, quite surprisingly, which grew on in the tank.  Around this time I had a chat with Mick Wright, a well known and respected fish breeder ( Preston & Dist. A.S.) Reassuringly for me, he was having exactly the same problem with habrosus;- despite all his efforts he couldn't trigger them to spawn. (However, soon after our chat, there was success for Mick!) Soon after, I moved some stock around, including the habrosus. I put them in a toffee jar and floated them in a tank which was around 5F cooler. The following day. the group were getting agitated at gravel level at the back of the tank, including a fairly plump female. Later on, that same afternoon, they were all "on the charge" so I left them to it.  I came back late afternoon and had to really search to find the eggs which were not only scattered all over the tank, but were laid singly in very differing locations. After much searching under every leaf and plant root, I managed to remove a grand total of only 6 eggs! (Three in the Java Moss, one on a Vallis leaf and two in the roots of the Java Fern under the bogwood but none on the glass!) Having bought the group as young fish, this was her first spawning but nevertheless, a whole afternoon's activity for a very small total! It then went worse - only 3 hatched, then I lost 2 of those three, leaving me 1 fry to concentrate on growing on, recording its growth and hopefully doing better with the next batch! Fry development  The single fry continued to feed well and at just over another 2 weeks on, had become an attractive, much bolder marked, smaller version of the parents..  I was then fortunate enough to buy 2 fairly plump females from an aquarist friend. Within two days one of the females duly obliged, yet I only collected 7 eggs which were all laid on the Vallis leaves. I immediately removed the eggs and put them in Meth Blue with an airstone. This time I managed 5 fry and when they were 5 to 6 weeks old, transferred them to the main tank. From this point onwards, spawnings are few and far between, so it's a case of collect a few eggs, hopefully add 3 or 4 fry to the main tank and gradually build up the colony. At the moment, not including the juveniles which are growing on, I have an adult group of 3 females and 5 males, which is the type of group balance needed to have at least a fairly active breeding situation. Summary So, if you are considering breeding one of the dwarf Corys, I would certainly recommend (only from my experience!) that you try C pygmaeus first. I found it easier to trigger them to spawn, more eggs were available and growing on the fry was a much easier process. Copyright; Text and photos. Ivor Hilton. |
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