Can I keep a crayfish with my 5 inch green severum and my 3 inch convict cichlid. They have a red one for $4 at the fish store. I just wondered if the cichlids would kill it. I had a crayfish for a few years before by herself in a 5 gallon (She was 3 inches long and loved tuna fish). I made the mistake of leaving her lid open. Now I have a breeding colony of spring peepers in the tank, so could I put the crayfish with the 2 cichlids in a 30 gallon. If not can I put a crayfish in with some bluegill and 2 red zebra cichlids (the bluegill and Red Zebras do surprisingly well together)? That tank is a forty gallon