If by mosquito fish you are talking Gambusias, you really do suck at aquariums. I like to keep a small predator and feed them Gambusias from a trough. I've broken ice to get them out and didn't bother to warm them up before dropping them into the aquarium. They always live. Drop them in hot sand, rinse them off and they're ready to go. I have yet to play with a tougher fish.
