Freshwater aquarium algae

There are many types of algae that are commonly found in a freshwater aquarium setting. Species may be unintentionally disseminated through spores and fragments that hitchhike on ornamental fish and plants purchased from aquarium suppliers. Algae is typically considered a nuisance and subject to removal through the use of algicides and the release of algae eaters. However, total elimination of algae is considered unlikely in a hobby aquarium.

Algae can be used as an bioindicator to inform an aquarist on water chemistry and other conditions. Some species are intentionally cultivated within algae scrubbers. Few algae, such as marimo or red moss, are sought after for aquascaping in freshwater aquaria.