Betta Fish: HELP! Is this mouth rot?

I do NOT think this looks normal, I just got this male betta yesterday and he’s been glass surfing every few minutes. He won’t eat, and he doesn’t seem to be normal. His tank parameters are 0 ammonia, 0 nitrites, 0 nitrates, 7.6 ph. He is housed with neon tetras and Harlequin Rasboras. He was already in a community tank at the pet store I got him at. Tank is 78 F, it’s a filtered 20 gal long with live plants.