i have a 250 gallon pond , i have 4 goldfish 2 are about 4 inches and the other 2 are about 6 to 7 inches and have no problems with mosquitos. the fish eat them . another thing you can do is put tadpoles in them they love them too. i don't know how big your pond is but if you feed them ever 2 or 3 days they will start eating them like they're candy . oh and by the way , i live in Kissimmee so i know what you mean by killer mosquito's.