Collecting, keeping and breeding an undescribed catfish species from Peru
By Don Kinyon (habitat and collecting photos by David Snell)
If ever you have the chance to venture to South America (or anywhere else) to collect your own fish, don’t think about it: just do it. In October of 2017 I was fortunate enough to be included on a collecting trip to the Madre de Dios area of Peru and I wouldn’t trade the experience for anything. We were able to collect a varietyof fishes, with our sights set on Corydoras species. One of the species that we found was a yet undescribed Corydoras: the CW124.
CW124 is an average size species for a Corydoras with the males reaching around two inches and the females just a little larger, perhaps two and one-quarter inches. This is a long-nosed species. The body color is a charcoal pattern over a white background, with the pattern being darker and more distinct on the males. The pattern coloration is darker near the center of the body and fades out toward the outer edges and the tail. The fins are clear for the most part, but on some individuals the first ray of the dorsal and pectorals fins is dark. Under light, the head will reflect a metallic green; again, more prevalent in the males. The female's body is a little more stout than the male, but the dimorphism is not as great as it is with others of the genus.
We collected these fish on pastureland in the Madre de Dios area. It was fair walk to the site from the road, but well worth it. The collecting area consisted of a small pool and outflowing stream. Water came into the pool from a very shallow, swampy area of the forest. The pool itself was perhaps 15 feet across, 30 or 40 feet in length and 2 feet deep. The stream flowing away from the pool was very small and shallow: in many spots you could walk across with one step and barely get your ankle wet in the middle. Most of the pool was exposed to the sun, so the temperature was much warmer than most keepers’ idea of Corydoras temps: 81°F. The farther downstream the water flowed into the forest, the cooler it became. The pH was between 6.5 and 7.0, TDS at 16ppm. We collected a variety of fish in the small pool and stream; Corydoras, Ancistrus, and Characins.
Most of the adult CW124 were found in the pool, while many of the younger of the species in the outflow stream. For conservation's sake, we only took adults and limited ourselves to 12: three pair for me and three pair for another member of our group.
Our guided collecting tour provider, Go Wild Peru, has an aquarium room on site with plenty of soft water at the perfect temperature for water changes, so keeping the fish healthy for the week was relatively easy. One of us (usually me) did water changes daily at a rate of 30 to 50 percent. All the CW124 were in very good shape when we left at the end of the week, and several weeks later when they were shipped to the US, they were still very healthy.
Once the fish came home, their new digs consisted of a 55 gallon aquarium; not because I thought the six fish needed that much room, but it was the only thing available at the time. I tried to duplicate the conditions of their natural home, filling the tank with almost 100% rain water and using two outside filters along with a small wavemaker for current. The bottom of the tank had a thin layer of brown sand. A few broad-leaved Anubias and some sunken wood gave cover for the wild fish. One yarn mop was hung near the wavemaker, looking like a bunch of water plants caught in the flow of the stream. pH was 6.0, TDS at 55 ppm, and temperature was 70°F; much cooler than their natural home.
The first thing that was noticed about this species is that they’re very active fish, and on the aggressive side (for Corydoras). The males almost constantly chased each other and sometimes the females would join in as well. There was a lot of bumping and sparring, but nothing that looked like it was a danger to the fish’s health. With all the activity going on, it’s probably a good thing the larger tank was the only one I had available for these fish at the time.
A few days after they arrived, one of the males was found dead; wedged behind the uplift tube on one of the HOB filters. I’m not sure what happened, whether it was the aggression of the other males or perhaps a wound or disease from the shipping process. None of the other fish showed any signs of distress.
After the new catfish had been in their new home for a few weeks, they became even more active and spent a good deal of their time swimming into the current produced by the filters and wavemaker. One morning while feeding them, I noticed that two of the females were swimming right into the mop which was still flowing in the current from the wavemaker. Removing the mop and making a quick inspection revealed many very small, dark amber colored eggs: about 1mm in diameter. That mop was taken to a hatching tank of around 6 gallons, filled with water from the breeding tank. I replaced it with a clean mop and set watch on the hatching tank. Besides the mops, the hatching tank held a sponge filter, a thin layer of sand, and some java moss.
It took two days for the first free swimming CW124 to emerge, and they were difficult to see in the brown sand. At that time, I checked the mop in the breeding tank. It was loaded up with eggs, just like the first, so it was added to the hatching tank as well. Two days later, the process was repeated, with more eggs in another mop added to the hatching tank. Now it was time to stop: no more empty tanks to put mops into and when the hatching tank was flashlighted after the room lights were out, so many fry were present that it appeared the sand itself was moving.
It was hard to estimate the number of young catfish, but I’d guess somewhere between 100 and 150 had hatched out in the small tank. This created a real problem with crowding. Call it a blessing in disguise or not, but I was kept out of work for several months recovering from rotator cuff surgery due to a misadventure with a log splitter. This was very good for my fish room maintenance, but not for all other aspects of life. With nothing but time on my hands, one-armed water changes once or twice a day became the routine. The changes were small at first; maybe 15 or 20 percent for the first few weeks, giving the young fish’s air bladders to develop, then larger changes of around 50% were the norm. Even in such a small tank, all the fresh water kept the fish healthy and the tank clean. Eventually, I started using tap water for the changes; pH of 7.2 and TDS of 140 ppm. There was no heater in the hatching/rearing tank and the temperature remained in the low to mid-seventies.
Feeding the young isn’t difficult. They always seem to be hungry and accept anything that they can fit into their small mouths. Microworms, decapsulated brine shrimp eggs, Golden Pearls and other micro foods were fed in rotation twice a day. Even with all the good food and fresh water, these Corydoras grow slowly. At three weeks they were just over one-quarter inch in length and at five weeks, barely three-eighths. They are very active both day and night, much like the parents and a very interesting fish to watch.
At this writing the young catfish are six weeks old and looking very healthy. Though not common in the hobby and quite possibly not imported to this point, I believe this Corydoras will be a popular fish in the future among both Catfish enthusiasts and general hobbyists. With the ease of care and prolificity of this fish, I don’t believe it will be uncommon in the hobby for very long.