Fish compatible with a Male Betta in a 10 Gallon Tank with a heater and filter?

Notorious fin-nippers include most barbs like Tiger Barbs, Tetras like Black Skirts, and sometimes mollies. Once your tank is cycled (which btw no tank can be fully cycled in 24 hours, cycling takes up to 2 weeks, during those two weeks you have to test for ammonia, nitrites, and nitrates to know when the cycle is over) I recommend Zebra Danios or White Cloud Mountain Minnows. Guppies' colorful tails can often become a target for the betta to attack and neon tetras have been known to gang up on a betta or the betta will sometimes chase and attempt eat them.