by Don Kinyon, uploaded January 01, 2002
In the tributaries of the upper Rio Negro in Brazil, there are a few small catfish with strikingly similar color patterns. Corydoras adolfoi, 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 size cory, attaining a total length of around two inches. 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. adolfoi, 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 zero, and between 68 and 76°F. There were several pieces of sunken wood and live pants in the tank, 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 thirty 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 two inches 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 thirty eggs from the glass.
I removed the eggs to a separate tank; a two-an-a-half gallon, with a bare bottom and 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 look like "an egg with a tail" and eat nothing, but took micro worms after that, and baby brineshrimp a few days later. With water changes twice a day at fifty 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 thirty 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, and seemed to have no ill effect on the young cats or tank mates. I was able to raise eighteen 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.
Thanks also to Dr. Sands, for taking the time to explain to me the differences in the similar species, and for the hints on breeding C. duplicareus.
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