Mayfly
From The Aquarium Wiki
Mayflies are insects of the order Ephemeroptera, from the Greek for "Short lived" and "Wing". They are very short lived as adults, living less than 24 hours.
Care
As larvae, they can be kept in an aquarium. One requirment is well oxygenated water, and mayflies also need algae as a food source.
Use as a food source
They can be used to feed fish that eat insects.