1.Replace the traditional HOB, canister filters --- Gone are the days when you got to change the cartridges and lter media almost every week. The handy filter by will do the same job economically and quickly. But please note that for it to function, you must connect the sponge filter to the air pump (not included). 2.Specially designed for betta, fry and, other small aquatic pets --- Betta, fry, and other small fish will NEVER get stuck into the filter. These fish, especially betta, generally don't like strong currents, they prefer calm and steady water. This filter is designed to have a slow current to easily let betta, goldfish, discus, dwarf cichlids, guppies, and krill fish continue breeding and spawning comfortably. 3.Provide supplemental food for fry --- The minor bubbles that are created by this sponge filter create a nominal current, adding in bubbling water. This will encourage them to continue breeding and spawning comfortably. Also, the sponge filter makes a home for fish food supplementing their daily dose of diet or food intake. 4.Perfect when used singly --- It only requires an air pump and airline tubing (not included) to work. These create numerous minute bubbles for increased oxygen flow. Simply connect an air pump to the top center filter, then place it in your tank. Please note, the base of this noiseless filter is not weighted, so you may need to weigh it down. It is suitable for tanks. Use 2 or more filters in larger tanks.