Corydoras Aeneus: A Very Common Catfish

We purchased a group of six very small skinny Corydoras aeneus last year from a local store. The looked like they hadn’t been fed in a very long time. Normally, I wouldn’t have purchased such fish, but since they were going to go into a 40-liter tank by themselves I reasoned that it was okay. MAY I SAY THAT I WOULD NOT RECOMMEND THIS! The main reason I purchased these fish was because they were the only corys available. I had the storeowner feed them so I knew that they were eating at least something. If they had not eaten anything, I wouldn’t have chanced it. They were also quite active.

Once I got them home I put them in the aforementioned 40-liter aquarium. I fed frozen bloodworms, brine shrimp, sinking wafers and algae wafers. They were also fed several different kinds of flakes. To my delight and surprise these fish ate and ate and ate. I called them my little pigs for a while. With all this eating they started to grow and fill out. Within two weeks they presented me with the first batch of eggs. What a surprise!

Over the next month, they continued to lay eggs all over the aquarium glass, I finally gave in and tried to raise some. I removed some of the eggs and put them in a 10-liter tank. The water parameters were the same as the 40-liter tank, with a temperature of 25C, a pH of 7.8, and fairly hard water. Some of these eggs hatched, but I didn’t consider it a very good hatch rate. Slowly over the next few days all the fry went to their demise. We blamed it on the water, as the water is harder here than where we use to live and didn’t give it much thought after that.

After these fish had been quarantined for three months, we moved them into the 240-liter barb community aquarium. They were still breeding in there as well, as eggs were seen quite often. One night as we were watching the fish that had just been fed, my husband yelled “Hey, what was that?” I looked and of course saw nothing. “I saw a baby something” he said. Ya, right. In a barb aquarium…I don’t think so. This happens to us quite often. I finally spotted it a few days later. It looked like a cory but it was tan and spotted. The corys I had were light gray with a dark splotch. Then after about another month the true colors came in and he looked just like his parents.

Now I realized that these fish could be raised in this water and that the problems of the first spawn was possibly because the fish may have been conditioned enough to spawn, yes, but not conditioned enough to produce strong eggs or sperm. Another possible factor could have been the age of the fish. They may have been too young. So we pondered all these thoughts for quite a while.

Seven months later, when we were doing a water change, very large plump corys were noticed. A very plump female of about two inches and a slightly smaller male were both moved into a bare 40-liter aquarium.

The next morning they spawned. I watched them for a while as they formed the T-position and then deposited the eggs on the glass walls. Then I moved them back to the 240-liter tank and they finished spawning in there.

There were approximately 200 eggs in the 40-liter aquarium. The water parameters were: pH 7.8, hardness 280 ppm, and temperature 25C. Nothing was used on the eggs for fungus, but a dechlorinator was used in the water. An air stone on very low and a heater were all that was in the aquarium. There was very little fungus with this spawn. The eyes could be seen on day one. In the morning of day two a dark line (spine) could be seen in the eggs. In the evening the eggs were bouncing and then all at once they hatched right before our eyes.

Micro-food was fed on day one after hatching. On day two baby brine shrimp was added to their diet. Not all were big enough to eat the brine shrimp, so they ate the micro-food. Water changes of 20% were done every night or every second night for the first week. Then 40% water changes were done about three times a week.

There were a few die-offs of the smaller fry for one reason for another. The power bar was shut off one evening to feed and found the next morning still off. The temperature had dropped to 18C. This caused a few more loses. I have to say though that we were very lucky not to lose the entire spawn.

At just over three weeks, Grindal worms were added to their diet. This seemed to cause some floaters.

Culling had to be done four times. We had planned to raise 50 fry so as they grew we culled some of the smaller ones out. It wasn’t until we had 50 left in the aquarium that we noticed that there were some tail deformities. Some had flat tails and some had pointed tails. Uh-oh, the biggest mistake yet. By the time we finished culling those with deformed tails, we only had 17 left. Perhaps if we had taken more time we might have noticed the tail deformities at a younger age.

My husband gave them all away when they were big enough to go to new homes. He also divided the spawning group up into two groups. The new owners came back and told him that both of them had eggs the next day. Then they asked him what they should do. Perhaps the start of new hobbyists?

In conclusion, I would recommend never buying fish that don’t look perfectly healthy. Give your fish a few chances at spawning if you are not successful raising the first few. Don’t over crowd the fry aquariums, but don’t cull down too soon either. Well, we learned and relearned from our mistakes, as this was our first spawn in a very long time. ?