Pretty soon, I'll be ready to swap out the 55 gallon for the 90 gallon tank. Once I do that, the tomato clown pair will go in the 30 gallon tank, along with 2 yellow tail damsels. That'll leave me a yellow tang, orchid dottyback and a bangai cardinal, in the 90 gallon. Do you think I could add another tang? Or is that asking for trouble?