Ok well, I'm moving my 2 Red Devils into the 75 gallon from the 55. So that leaves it open for the Bucktoothed Tetra. Problem is I want him in there because I want him to grow to a wild size, but thats a small fish for a big tank. And as I recall you cant keep anything else with them, not even there own kind. But I bet if I got 3 more (totaling 4), they mite not fight and just mite get along. What do you guys think?