Easy-to use biological filter for tropical aquarium fish Aquarium filter sponge for efficient biological filtration Great biological filter for breeding or spawning aquariums The filters allow you to cultivate nitrifying bacteria for superb biological filtration. Great for fry aquariums and brine shrimp hatcheries because they prevent young fry from being trapped in the filter media. Operates silently, creating numerous minute bubbles for increased oxygen flow. Each requires an air pump and airline tubing, sold separately. Produced from high quality hydrophilic filter material. The design provides large surface area for optimum filtration. Provides the ideal location for bacterial colonization. Operated by an air pump to create numerous minute bubbles to increase dissolved oxygen content. Replaceable filter sponge allow long lasting use. Does not trap fish fry. Suitable filter when breeding and spawning Discus, Dwarf cichlids, guppies, and killifish.