Freshwater clams filter food and nutrients out of the water. If they are in an aquarium, their diets can also include invertebrate food to supplement their natural food intake.
Because freshwater clams filter detritus and uneaten food from the water, nitrate levels lower and water quality increases in freshwater aquariums. These clams bury themselves in the substrate, leaving only their siphons above ground to continue filtering the water. Freshwater clams should be removed from the tank and placed in a different tank if copper-based medications are added to the water. They should not be returned to the original tank until chemical filtration has removed all traces of the copper-based treatment.