[Scleromystax sp. C112] Corydoras sp. "Baianinho II"

by Don Kinyon

This species has not yet been officially described, though I’m told they’re working on it. It is native to Brazil, but the specific system or systems that it comes from is sometimes debated. They very much resemble a small Corydoras barbatus, having the long snout and coloration of that fish, but only reaching about three inches in length. The pattern of both sexes is also similar to the larger species, but the males don’t seem to get the jet black-on-white during breeding; they are more of a dark charcoal.

I was able to get a few of these Corys when they were still a fairly "new" fish, but along with them came some kind of malady that wiped out every one of them, along with quite a few other species I was keeping before the affliction ran its course.

More than a year later, I received a group of young fish from a private breeder, and was able to raise a few.  They were housed in a Corydoras community tank, the way I rear most catfish for space’s sake, with several other species.  I first noticed some eggs in the tank and wondered from which catfish they were.  I removed the eggs, but none were viable. By watching the tank a little more closely, I was able to determine which of the Corys were spawning, and removed the male and three females to another tank.

The breeding set-up was a simple cube style tank, bare except for a single stone with some Java Fern attached to it and a couple small pieces of sunken locust wood.  A large power head provided filtration and current with a sponge filter attached.  The outlet of the power head was fitted with a hose for aeration.  Water was straight from the tap; 7.4 pH and 140 ppm total hardness, kept at room temperature; between 72 and 80°.

In this set-up each female spawned about once every ten days, producing an average of sixty eggs, but none were viable.  The eggs were laid in plaques, much like C. barbatus, usually close to the water line, and usually in a corner near the current.

By changing the water slowly over to softer, more acidic rain water, I was able to drop the pH and get the hardness to near zero in a few weeks.  The very first spawn after the pH reached six had a fifty percent hatch.  Subsequent spawns proved to be less successful if the pH rose or fell too far from that mark.  I was never able to achieve much over the fifty percent level, but the ratio of one male to three females probably made it difficult.

I scraped the eggs from the glass with a razor blade and put them into a plastic "shoebox" for hatching, using water from the breeding tank and a small amount of acriflavin.  I kept an air stone in the shallow pan and changed ninety percent of the water twice daily.

In five days, the eggs hatched and the young catfish were mobile.  In another two days, they started feeding on micro worms, which they lived on for the first week.  After that I added decapsulated brine shrimp eggs to their diet.  I have had some very bad luck feeding young Corydoras on brine shrimp nauplii, so I no longer use them, but use the decapsulated cysts instead.  The fry eat these readily, and grow just as quickly without the terrible problems I had using the hatched shrimp.

When the fry were three weeks old, they got their own tank, a 15-gallon, and I got a reprieve from the twice-daily water changes.  The only way that I have found to make this transition is to leave the new tank as shallow as the old container and add water very slowly, over a period of days, until the preferred level is reached.  The small catfish have a very delicate air bladder, and if water level changes are made too quickly, it can be damaged and kill the fish.

The youngsters lived in this tank until they were over two months old, and got a water change every third day of about fifty percent.  At about a month old, they ate the same foods as the adults, though it sometimes had to be chopped up a bit.  They grew very well and most were over half an inch by two months.

These fish have proved to be a little harder to keep and spawn than the average Corydoras, but the benefits are well worth it.  They are enjoyable to have in a community or species tank, and are always easy to sell or use as trade-bait for some of the other fish that you are lusting after.

This article first appeared in PVAS’s Delta Tale, Vol 33, # 1