Becca
Members
What I have read, although these were people keeping rainbowfish in tubs, is that mosquito larvae is fine and a source of food but dragonfly bad.
The bigger concern with mosquito is location of the tub if your state/county/local spray for mosquitos.
Rachel said mosquito larvae eat baby fish. I'm sure it does, in part, depend on what kind of fish you're breeding and how small they are when they hatch.