1.This mini sponge filter for cultivating oviparous fish, fries, fish eggs such as guppy, platy, etc. and it is the most suitable to cultivating opercular is and black carps, etc. in fish tanks. 2.Quiet environment: This air-driven mini sponge filter creates a gentle flow without causing disturbance to you or your fish. 3.With multi-layer sponge filters: this biochemical mini sponge filter combines physical and biochemical filtration for your fish and increases the oxygen solubility. The top layer of black bio sponge provide biochemical filtration and support colonization of beneficial bacteria. Efficiently remove waste and maintain clean water for your fish. 4. Easy to set up & clean: simply install an airline into the unit and turn on the air pump, simply rinse and squeeze sponge in tank water.