I'm so sick of hearing that! I currently have a few red eyed tetras (beginning to stock my 20 gallon) and all they do is hide. I cycled the tank with them (didn't know enough not to listen to the lfs employees who said it was okay for them). My water seems fine (Ph 7.4, ammonia 0. nitrite 0, nitrate 5). Is that just how they are? I just added a couple of rummy nose and THEY swim around. It seems like the red eyes are wasting perfectly good fish space! Is this common?