Infusoria's an obsolete collective term for minute aquatic creatures like ciliates, euglenoids, protozoa, and unicellular algae that exist in freshwater ponds. In modern formal classifications the microorganisms previously included in the Infusoria are mostly assigned to the Kingdom Protista. Aquarium use Infusoria are used by owners of aquariums to feed fish fry; rasboras and bettas are just two examples which will require this food to survive the first few days. However there're usually not en… (More on Infusoria)