Corydoras duplicarius

by Don Kinyon

In the tributaries of the upper Rio Negro in Brazil, there are a few small catfish with strikingly similar color patterns. Corydoras adolphoi, Corydoras duplicareus, Corydoras serratus, Corydoras imitator, and Brachyrhamdia rambarrani are a few. Of these, one of the most colorful and rare is the C. duplicareus, described by Dr. David Sands in 1995.

Corydoras duplicareus is an average-sized Cory, attaining a total length of around 2". Both male and female have a light-colored lower body, gradually changing to a jet black on the upper half. There is also a black stripe over the eyes. The fins, for the most part, are colorless. The most striking feature is the bright orange/gold mark that starts just behind and above the eye, and ends just in front of the dorsal fin. Looking at the fish from above, the mark forms a "V" pointing to the dorsal.

I found a group of these fish marked as "Corydoras Cats" in a pet shop. Thinking that they were C. adolphoi, which are very similar, I bought a group of seven. The fish were fairly young and were kept for almost a year in a tank by themselves as they grew. I was later sent another pair of these fish by a friend.

All the fish were kept in a 30 gallon long tank, kept at room temperature, filled with collected rain water. The pH was 6.0 to 6.3, hardness close to 0°, and temperature between 68° and 76°F. There were several pieces of sunken wood and live plants in the tank and the bottom was covered with a light-colored gravel. Filtration was performed by a powerhead stuck into a large sponge filter and hung in the corner. Water changes were done at 30 percent weekly.

As with most Corydoras, feeding was not a problem. They ate all that was offered, including live, frozen, freeze-dried, and flake foods. They seemed to be particularly fond of live white worms.

When the fish got to be close to 2" in length, I started to notice eggs attached to the aquarium glass, usually near the current caused by the filter. There were never a large number of eggs at any one time, but the fish spawned almost constantly, it seemed, and in a few weeks I’d gathered 30 eggs from the glass.

I removed the eggs to a separate tank: a 2 1/2 gallon, with a bare bottom and a small sponge filter. A few of the eggs were infertile and developed fungus, but most hatched seven days from spawning. For a few days, the babies looked like "an egg with a tail" and ate nothing, but they took microworms after that and baby brine shrimp a few days later. With water changes twice a day at 50 percent, the young fish grew even in their small home, but in two weeks they had outgrown the tank, so they were moved to larger quarters.

The young fish grew very well in their new home, another 30 gallon tank that they shared with some other species of young Corydoras, along with some Rainbowfish fry and young Killis. Slowly, over several weeks, the water in the rearing tank was replaced with tap water that seemed to have no ill effect on the young cats or tank mates. I was able to raise 18 fry from the eggs collected, and started to notice more small fish in the parents’ tank. Apparently, I’d missed quite a few eggs and the adult fish didn’t view them as dinner.

At this writing, the oldest of the fry are ten weeks old and doing fine. In the original breeding tank, there are the adults, some ten-week old fry, and gradually younger fish down to a few days old, all living at peace with each other.

For More Information:
Aqualog - All Corydoras, Glaser, Schafer & Glaser, p. 74, pictures & text
Back to Nature Guide to Catfishes, Dr. David Sands, pp. 43-44, pictures & text

Note: Thank you, Dr. Sands, for taking the time to explain to me the differences in the similar species, and for the hints on breeding the C. duplicareus.

This article first appeared in PVAS’s Delta Tale, Vol 31, # 3-4

© Potomac Valley Aquarium Society, Inc.