I did a fresh clean of my 20 gal tank around 5 days ago. My 5 small gold fish, 1 angel, 4 black skirt tetras have been doing fine for 5 days. I just bought a beta and put him in around 9 hours ago, but he looks like hes breathing hard, he still has his dark colors, but he stays at the bottom of the tank laying side ways. And sometimes when he moves, he really moves fast. I dont know whats wrong, my other fish have been in the tank for 5 days and they look fine.

I would say check your water but bettas are fairly hardy. Firstly i have to say mixing you have going on there isn't right, goldfish do not belong with tropical community! But if it works for you enjoy :). Your bettas breathing may be caused by stress (i.e fin nipping from the angel fish) angel fish and bettas should not be mixed for this reason. I would isolate him and see if he improves. How long he was in the tank? Bettas from pet stores usually aren't well taken care of, he may have been on his wits end and the stress of the other fish may have sent him overboard. I wish you good luck though! Hope he gets better!

a small bowl may help but it may be the age of betta and were u baut it some stores have older fish shipped are younger

I never thought I'd hear myself say this but right now your betta would probably be better off in a bowl until you can make other arrangements for it.

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Doing a fresh clean of the tank will destroy all the beneficial bacteria it had in it, so basically you're starting over from scratch
5 goldfish is severely overstocking a 20 gallon and the others are not compatible and will very likely start showing signs of stress in the next few days.
The betta's probably stressed and shocked. If you have a larger container for it I would suggest replacing some of the water with new conditioned water and seeing if that helps
Best of luck