This Pawfly mini aquarium sponge filter is designed for small fish tanks. It provides biological filtration, helping to maintain clean water. The filter is suitable for use in shrimp tanks, breeding setups, or hospital tanks where gentle water flow and safe filtration for small fish and fry are beneficial. As a new item, it is ready for use. Free shipping is available. The sponge material offers a surface for beneficial bacteria to colonize, aiding the nitrogen cycle. It is an internal filter powered by an air pump (not included). A practical choice for hobbyists seeking a simple, low-maintenance filtration solution for compact aquariums. Check the listing for full details on dimensions and compatible tank sizes. Pawfly Mini Aquarium Sponge Filter, Small Fish Tank Internal Filter. Condition: New. Listed at 14.99 USD. Aquarium Small Fish Tank Filter for Breeding Fry Betta Shrimp Tanks. Small Internal Filter: 2.13" W x 2.4" H. Fit for fish tanks up to 5 gallons. Prevent them from entering the aquarium to keep water clean.