Types of Worms encountered in aquaria: most are Fish Food
A. cyanostictum munching on a white worm.
Worms have long been understood to be an integral part of many - tropical fish's diet. While most killifish eat ants that fall from trees a few eat primarily aquatic crustaceans and worms instead, for example the Diopteron subgenus in Aphyosemion. But worms will put all killies in top condition for breeding and it's no wonder aquarium books suggest "condition for breeding by feeding worms". It really does work, nothing else seems to work as well. Fortunately they're very easy to culture, clean and disease, alage and pest free.
David Ramsey found that mites and gnats that infest worm cultures can be safely killed with BT (a biological larvacide called BTI (Bacillus thuringiensis subspecies israelensis - is a naturally occurring bacterium that's deadly to both mosquito larvae and fungus gnat larvae.) which does not affect the worms or fish. Dvavid has a video here
