How old do corydora aeneus get? I am arguing with someone on Youtube about the size of a shoal and the size tank. He said that having a minimum group of 6 corys or any schooling/shoaling fish is a myth. And that fish do fine in a group of 3-4. He claims he had 5 corydora aeneus in a 10 gallon for 11 years, which I have doubts but do believe it can be possible but it most likely wasn't an enjoyable life.