There are two kinds of flies that could be called “aquarium flies”. There are flies that people do not want in their aquarium – these are pests. There are also flies that people raise to feed to their fish.
One of the common pests of standing water is the moth fly. It has other names, including drain fly, filter fly, and sewage fly. There are several species of moth flies. They belong to the family Psychodidae.
Moth flies get their name from the fuzzy appearance of their body and wings. Since they are flies, they only have two wings, rather than the four wings that real moths have. Most moth flies are tiny insects. Some are as small as 1/16″ long.
These tiny flies get the name of drain or filter fly from the kinds of places where they breed. The adult flies deposit their eggs in slimy residue in places like drainpipes. The larvae eat the slimy material and develop in it. Some aquarium fanciers report finding that the fish ignored the larvae since they were completely hidden in the slimy substance where they were growing.
Cleaning will eliminate these flies. Remove the slime where the larvae are developing. When there is no place for the adults to deposit their eggs, the problem will disappear.
Some fish breeders raise small flies to feed their fish. Many of them use a different type of fly. The one that many aquarium-keepers use is the fruit fly. These are also tiny flies. They are usually tan-colored and the most common ones have bright red eyes.
These fruit flies are popular with fish breeders because they grow very fast. Many breeders have special rearing chambers for the flies. These chambers keep the flies from escaping to the kitchen where they would invade the pantry to find vegetables or fruit. The breeders make a special culture medium for the lies to eat. Some of them are willing to share their recipe, but others prefer to keep it secret.