Corydoras Paleatus
Though the cats are very seldom bred by the amateur, they will breed rather easily and very interestingly. Let us consider Corydoras paleatus as the typical catfish for the home aquarium. The Corydoras are small members of the family Callichthyidae and are very well suited for the small tank. Corydoras are among the most popular of tropical fish, not because of beauty, but for their great assistance to the keeper of an aquarium in his cleaning. C. paleatus also breeds to a large extent like many of the more beautiful fish kept in tanks for esthetic reasons.
Since sex in the Corydoras cats is very difficult to distinguish, breeding must be accompanied by natural pairing. Some authors think that a comparison of the ventral fins will offer a sexual distinction. This method is difficult to use, not only because the fins are so similar in shape, but also because the cats are nearly always in a position that makes comparison of the ventral fins impossible. The ventral fins are important in the reproductive cycle of the fish.
Should you have half a dozen mature cats in the same tank, you might notice a male staying very close to a female, showing her more than a usual amount of attention. After a few hours of close movement on the bottom of the tank, the female will assume a position across the male that will facilitate her catching his flowing milt in her mouth. This milt is nearly invisible; the author has attempted on various occasions to introduce some sort of dye into the male that might color his sperm but has had no success.
It seems that as soon as the female has the milt in her mouth she drops a few eggs, catching them between her ventral fins. She then leaves the prostrate male and searches for a suitable location for her eggs. When a stiff leaf has been selected, she touches the spot with her mouth, there depositing some milt, and then presses a couple of eggs into the milt. She repeats this process very shortly to dispose of the remaining eggs she has clasped in between her ventral fins. The female will then return to the male.
The female does not usually drop all her eggs in one place; she more often seeks a new place for each group of eggs. Different types of cats are interested in different types of locations, some choosing the glass, some even a bubble-nest (Hoplosternum).
The eggs hatch in a few days, and the young immediately disappear into the muck on the bottom of the tank, where they seem to stay for a few weeks until they are large enough to handle fairly large-sized food (grown daphnia). They mature rapidly and seem very hardy. The parents show little interest in their brood and, if well fed, usually will not disturb the eggs. Other cats will not bother the brood either.
Among the other types of cats that are popular are the bronze corydoras (C. aeneus), a type that breeds by the female placing her eggs on glass; the leopard corydoras (C. julii), a very active fish; C. nattereri, which is very similar in all respects to C. paleatus, though slightly darker; and the large, 4-inch C. agassizi.
All these corydoras catfish are peaceful, very hardy, and excellent as scavengers. They will do especially well if kept on a diet of live food (tubifex is best; cats can often dig it out of the sand by burrowing, while it is usually too deep to be pulled out by the more ordinary types of aquarium fish) and in a tank of their own. Best breeding results will be obtained if a blanket of litter is allowed to accumulate on the bottom of the tank so the fish may hide when they feel shy. This cover will also be beneficial to the young Corydoras. Water changes greatly stimulate spawning activity.
