in my 55G. Two are about a year old and I added a young one about a month ago. The two older ones are about 5 inches long already and growing. My LFS
has an elderly 8 year old. Lovely but almost 9 inches!! So your going to need s p a c e. I did however house the two older ones in a 20G, but only for a short time till I got one of my 55's up and running. They were about 1 1/2 inch when I got them. I just love these guys. They have taken to pecking me when my hand is in the tank. No eggs or such, just a peck and run game! LOL Here is a pic of my 1 year old.