Got a small fish tank or bowl? This XEOGUIYA mini filter is perfect for keeping the water clean without taking up much space. It's only 9.8 x 3cm, so it fits nicely in tanks from 1-3 gallons without being obtrusive. The cool thing about this filter is it's a 3-in-1 system that handles mechanical filtration, biological filtration, and increases oxygen all at once. It uses a biochemical sponge that develops beneficial nitrifying bacteria to break down harmful waste products. The design includes funnel air outlet, air stone filtration, and biochemical filter cotton - so it's doing multiple types of filtration simultaneously. Important note - you do need to use this with an oxygen pump (the pump isn't included), but don't use an oversized one or the water and air won't mix properly. Installation is simple - just connect the filter to your air pump with the tubing, plug in the pump, and you'll see water or bubbles coming from the outlet. It comes with powerful suction cups that make it easy to position exactly where you want it in your tank. Regular maintenance is easy too - just rinse or squeeze the sponge in aquarium water periodically. Great for small fish, shrimp, or fry tanks where space is limited but you still want good water quality.