I have a 29 gallon semi-planted tank. We cycled the tank then put in fish about 3 weeks ago. We put in 2 albino corydoras and 3 peppered corydoras and only realized that they had to be in groups of 4+ of the same type after we got them. By then it was too late, and due to the covid-19 situation, we weren't able to exchange or rehome the fish. The weekend after that, we put in 6 tiger barbs. All of the fish are juvenilles and the corydoras and barbs are all smaller than 2 inches. Most of the barbs are a bit bigger or equal in size to the corydoras. There was a bit of fin nipping and I noticed that almost all of the peppered corydoras fins showed some tears + damage. Both of the albino corydoras fins were also a bit nipped but considerably less. The barbs only chase the peppered corydoras around. I thought all of the fish were getting used to each other, but this morning, I found my smallest peppered corydora dead. He was alive last evening, but I checked this morning and his eyes were pecked out and he was lying motionless at the bottom of the tank. The two albinos are fine but my other two peppered corydoras seem sort of traumatised. One is hiding behind the filter and not moving and the other is stuck on the upper side of the tank under one of the plant leaves (also not moving). I feel horrible and they seem really pathetic. I'm not sure what to do, considering I can't return them back to Petco where they would have a larger school and I don't really want to get more corydoras and subject them to the same suffering.
I'm also not sure why the corydora died because the tiger barbs didn't seem to gang up on them and bite him. They usually only bit him if he was close to them and sometimes even ignored him. The fish's dead body also didn't really seem to be torn up or eaten and all of the fish were ignoring it in the morning.
Another problem is that I'm not sure the corydoras are getting enough to eat. I thought that the tiger barbs wouldn't bother with the food that falls to the sand but they're actually a better clean-up crew than the corydoras and leave almost nothing for them to eat. I've tried putting in a bunch of food so that some falls to the bottom and even tried spot feeding at opposite sides of the tank. Nothing worked. It doesn't help that the corydoras seem almost blind and often swim right past food. The albino corydoras are often a lot more active and end up at least getting a morsel or two. But the peppered corydoras hide most of the time and I'm concerned that they're not getting enough to eat. What should I do??
I'm also not sure why the corydora died because the tiger barbs didn't seem to gang up on them and bite him. They usually only bit him if he was close to them and sometimes even ignored him. The fish's dead body also didn't really seem to be torn up or eaten and all of the fish were ignoring it in the morning.
Another problem is that I'm not sure the corydoras are getting enough to eat. I thought that the tiger barbs wouldn't bother with the food that falls to the sand but they're actually a better clean-up crew than the corydoras and leave almost nothing for them to eat. I've tried putting in a bunch of food so that some falls to the bottom and even tried spot feeding at opposite sides of the tank. Nothing worked. It doesn't help that the corydoras seem almost blind and often swim right past food. The albino corydoras are often a lot more active and end up at least getting a morsel or two. But the peppered corydoras hide most of the time and I'm concerned that they're not getting enough to eat. What should I do??