Sounds like a population problem to me. That is if you keep going like you're talking about. You're looking to put agressive fish in a small tank. Not a wise choice. I've never seen a white tail trigger but imagine it gets as large as the others. Do you mean a pink-tail trigger? If so then they get about a foot long and need much more space. You're safe for now but once your damsels grow you will have a population problem depending on which ones you have. There are nice combos you can do with a 25 gal tank (too many and not enough time right now to explain all this) but not one combo that should be done as an agressive tank with triggers and puffers,etc,etc. Good luck and please don't look into getting anymore fish for it. Seems you have enough. Perhaps get rid of some of the damsels and add another type of small fish to the tank.