I have a gold wolf thats a little bit shy of five inches that I had to remove from my 90g. He was with parrot fish of similar size to twice his size and was being too aggressive. He just removed the tail of my convict parrot and during feeding (pellets and krill) he is very rough on the others. I was going to leave him in the tank, but he is just waiting to finish off the parrot he mangled and I am afraid he will move onto the others eventually. The only tank I had available was a 20 long, so that is where he is going to reside for now. My question is till about what size do you think he could stay comfortably in that tank? I normally wouldn't pose this question with a wolf, but since he is a gold he is very active. I have a 50g, which will hopefully be to grow him out for awhile, but it will be some time before I can move the fish that are currently in the tank. As a result, he will have to spend some time in the 20. Thanks for the help.