How to choose a filter for a Betta tank

[lumin5]

If you're using a sponge filter, don't forget to get an air pump with adjustable flow. That way you can tweak it if the bubbles are too much for your fish.

[ocean8]

Yeah, and if the sponge filter's too weak, you can always upgrade later. Better to start gentle and adjust as needed.

[folkstar]

Remember to monitor water parameters closely during the first few weeks. New filters can sometimes cause mini cycles if not properly established.