1.With multi-layer Sponge Filters: this corner Sponge Filters combines physical and biochemical filtration for your fish and increases the oxygen solubility. 2.Quiet filtering system: The Sponge Filters good for breeding small fish. Efficiently remove toxic waste and maintain clean water for your fish. 3.Easy clean and maintain: just take out the sponge and rinse well when it becomes dirty. 4.This Sponge Filters are excellent for small size fish like dwarf cichlid, guppy, killifish, shrimp etc.