i agree dont do jacks or green terrors, and cellodaisy is right, turtles can have wide ranges of personalities, so the terrors and jacks may fit in a 55 when there small, they certainly wont like having the turtle in there. so that can play out 2 ways, 1st the turtle is a coward and wont do anything he will just take a beating, possbily get an infection may lead to death may not, 2nd way turtle starts to get annoyed with the fish nipping at it and decides to start nipping at the fish now you got dead fish.