Betta Fish: What’s my betta doing 😭😭

It looks like he’s just flaring and trying to assert dominance over whatever you were showing him. Male bettas do this regularly and many females have been known to exhibit this behavior as well. Before I quit smoking I once showed my betta my cartridge and she flared at it lol. I’d never had a female do it before but she sure showed me. The swimming back and forth is part of the aggression he’s performing and should stop when he’s not angry anymore. If he’s swimming all along the glass when he’s not flaring it could be because he’s stressed or not yet used to his new environment.