In my opinion, small fish tanks are anything under 20 gallons.
Anything under 5 gallons would be a nano tank, but for this article, I won’t distinguish between the two.
With that in mind, when talking about small fish tanks, filtration becomes a significant challenge, and the smaller the tank, the more critical filtration becomes.
This is why you need a small fish tank filter that can fit in a tank 10 gallons or less but still provides you with top quality filtration to ensure your tank remains healthy and clean.