HITOP Diameter 4in Aquarium Bio Sponge Filter: 5-40gallon Air-Powered Fish Tank Filter, Quiet Filter for Aquarium/Betta Tank/Shrimp Tank/Fry Tank

https://www.amazon.com/HITOP-Round-Aquarium-Sponge-Filter/dp/B0CL9F957P/ - already has built-in airstone for smaller gentler bubbles + love the round shape. AND this pump kit: https://www.amazon.com/Aquarium-Air-Pump-All-One/dp/B0B1ZYY4RG All you need to have a safe gentle filter for your betta.Basic setup: https://www.youtube.com/watch?v=BS7gIHUkhuo