Corner-shaped Design: Expanded surface area for better air diffusion and oxygen circulation. Hides neatly in the tank corner, saving space and maintaining the tank's landscape layout. Fine Sponge Filtration: Provides mechanical and biological filtration, trapping debris and waste without harming fish, helping keep water clear. Small Size: Measures 8.4 cm (D) x 12 cm (H). Ideal for 20-40 litre small fish tanks. Suitable for breeding and feeding ornamental fish, shrimp, or fish fry. Easy to Clean: Filter can be easily detached for cleaning. Rinse every 24 weeks with aquarium water only. Do not use tap water. Quiet Aeration: Air powered (air pump not included) and operates quietly without disruption. Press the sponge into the tank to saturate with water and sink to the bottom.