I know some here don't like it when their bettas bite them, but it always amuses me when mine do! Hai there little piranha wanna-be! The males like to show me they mean business by attempting to take my finger off. If they were like...10x bigger they might have a shot
My little girl will come delicately, almost politely nip. Just sounds like your boy is feeling feisty!
I fourth or fifth the cup recommendation. I get them at the top, distract, put the cup under behind them and suck them in. This works great on my big finned males. Its more challenging with Sapphire - she's *fast* and can swim out even against the current if I'm not super quick. They don't particularly like being cupped, but a pellet while they wait usually mollifies them
The Boy Feesh: Indigo CT, Lavatail CT, Ghost CT, Chicory HM, Redfish VT, Magic DT
The Girl Feesh: Christmas CT, Shine VT, Snowflake CT, Stripes VT, Midnight CT, Grif VT, Tangerine VT, Wraith CT, Amethyst VT, Ice CT, Poe CT, Turquoise II CT