Aspidoras pauciradiatus

by Don Kinyon

Here is something a little different for the Corydoras catfish nuts: an Aspidoras. This little gem was described by Weitzman and Nijssen in 1970 and classified as a Corydoras. It was later put into the genus Aspidoras.

This Aspidoras species have generally the same body as their close cousins, favoring the shorter-snouted species with a more straight-ahead mouth, such as Corydoras pygmeaus or hastatus. They are small, not reaching more than 1 1/2". The adult fish are silver or white with black markings: spotted along most of the body, with stripes or a blotch on the dorsal fin, and wavy stripes on the tail. There is no eye stripe common to many Corydoras.

In the swiftly flowing, well-oxygenated waters of the Rio Araguaia, Brazil, these little catfish are at home. When one can duplicate these conditions in the home aquarium, the fish thrive. My particular setup used a 35-gallon cube-style tank filled with rainwater; pH of 6.0 and total hardness near zero. I placed a large power head with a sponge filter attached to it in one corner and turned it to its strongest setting. The outlet had to be drilled to accept an airline, and a second air line attached to a diffuser was placed near the current. A single stone with a small Java Fern grown to it, along with some small bog wood pieces in the center of the tank, completed the setup. No heater was used, so the temperature fluctuated between 70 and 78°. The end result was a whirlpool of very oxygenated water.

My six male and seven female catfish were active in their new environment. There was a spot near the rock where the current wasn’t quite as strong that they could rest on the bottom, but most of the time they would swim in small groups into the current near the pump outlet. 

I gave them as varied a diet as I could, rotating between live, frozen, and dry foods. The diet was heavy with high protein and high fat foods, such as beef heart, white worms, chopped earthworms, black worms, and daphnia. It took only a few weeks on this diet for the females to become so gravid that they could no longer rest flat on the bottom; when they tried to, they "teetered". The fish seemed very happy and healthy with the surroundings, but I noticed no spawning behavior.

Working with Corydoras species usually makes a person more in tune with the barometric conditions. If you keep watch of the barometer, it makes it a little easier to spawn some of the armored catfish, and probably many other varieties of tropical fish. 

One evening when the barometer took a radical dive, I removed about 80 percent of the tank water and replaced it with much cooler rainwater. This brought on an immediate change in the fishes’ behavior. All the fish began to swim vertically up and down the glass at the outlet of the power head. The next morning, they were still at it, but no spawning. They kept the same pattern up for the whole day, so that evening I did another drastic water change. There was little change in the morning of the third day, and although I hate to let work take time away from the fish room, I had to leave them. 

Upon my return, I noticed the eggs on the glass, near where the group had been swimming for the past two days. They were still at it and continued until the lights went out that evening. I let them go one more day, then removed the adults to another tank. I counted about 20 eggs on the glass, in the plant, on the filter, and in the long algae growing on the bottom of the tank, but I assumed there were more. They were small and clear, and most seemed to be placed so that they would be near the current from the power head.

Within the next few days, some of the eggs turned white with fungus, but most did not, and five days after the spawn a few fry could be seen among the plant roots and strands of algae. After they were swimming for two days, they were given micro worms. I had only seen a few youngsters at a time at this point, and was curious as to how many there may have been. When it finally got the best of me, I reached in and pulled the stone from the bottom of the tank to see what was under it. This may not have been my best idea. I spent the next twenty minutes or so finding a place to set it back down without crushing baby catfish. As soon as I had taken the stone off the floor of the tank, an avalanche of fry fell from the plant roots and leaves.

After that lesson, I left them alone, save for water changes and feeding. Water changes were done twice weekly, at a rate of 25 percent, and feedings were twice daily and restricted to micro worms and newly hatched brine shrimp. With this schedule, the fry grew steadily, though not very quickly.

At one month of age the youngsters could be seen a lot of the time, searching for food and coming to the surface for a gulp of air. They were ?" by this time and starting to show some of the characteristics of the parents. Some flake food was added to their diet about this time and they took to it with gusto.

By the time the young were two months old, they were something to see. They were 3/4" in length and their tails had grown disproportionately to the rest of their bodies. It seemed to be twice the size it should have been. On top of that, the whole of their tails was jet black. The effect on the observer was comparable to that of a puppy with too-big feet. They were eating much the same foods as the parents at this time and were out in the current most of the time.

At this writing the fish are three months old and have lost their oversized tails. They are still quite pleasing to look at, much like the adults in appearance. The adults and fry are now housed in the same tank, and it gets harder all the time to tell them apart.

This article first appeared in PVAS’s Delta Tale, Vol 32, # 1 

 

© Potomac Valley Aquarium Society, Inc.

 

 

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