The External Cycle Breeder Box includes an air pump connection for air-driven filtration and water circulation.  With an air pump (not included), clean water flows into the top of the tank where debris is pulled with the water flow into the sponge on the side.  The sponge is removable for easy cleaning, and there is room to add several pieces of Active Filter 4-in-1 (also not included) for extra filtration. The included slotted divider provides better functionality for breeding. The size of the slots allow small baby fish to pass through, but keeps the parents away, preventing unwanted eating of baby fish.  To use this product as a feeding/quarantine tank or acclimation tank, you may easily remove the plastic divider. 9” x 4.75” x 5.5” Includes: Lid Suction Cups Slotted Divider Sponge Uplift Tube Return Spout Air Stone.