Mosquito larvae are an additional food you are able to collect from ponds. They may also be discovered in rain water butts, or even puddles. They hatch from the mosquito egg in a couple of days, and are easily recognised by their wriggly movement.
Their average length is about 0.25 inches, with a knob of a head on a worm-like body, with a Y-shaped end. They should not be given to fish under about 1.5 inches in length as the fish can effortlessly choke themselves.
It is as well to point out that as daphnia and mosquito larvae might be collected from foul pools, they should be rinsed prior to putting into your aquarium.