Appearance[]
They are small water crustaceans also called the Cladocera, around 620 species have been recognized now, they are flea looking and look like small, transparent disks in the aquarium.
Behaviors[]
They are a parasite that may transfer sickness to your fish. It is hard to get rid of their eggs because of egg resting, it means their eggs can stop developing for a bit to endure harsh conditions. They swim in a tank, then attach themselves to a fish. If you see transparent disks on your fish around the gills, bring it to the vet!