I agree with Book Shel's post. This is a wait and see, chances are he bruised the area and may have strained something and is babying the fin until it heals up which may take several days. Luckily fish are pretty resilient, we had any beta's, goldfish and especially tropical like the zebra and black mollies, red swordfish that over zipping around in the tank and would either wedge themselves in the decorations - too fat to fit through their building doors, windows or holes in the decrotative fencing, or the buggers would jump out of the tank, always aiming for the bright light at the top where the tubing ran in. That was a 3/4 inch hole and for whatever reason they would jump the tank and and on the carpet. Most of the time we found them within the first few minutes, the dog. Usually heard the splash and would bark like mad,but on occasion we found them almost dead, gasping for air dried on one side pretty much and we put them back in whee they sank and hovered for several days. About the time we figured to end their misery they soulful be back to zipping around being their normal obnoxious selves. We ended up lugging the hole with the white filter batting since the small piece of plastic we had kept getting knocked off. Dint have the problem after that. Also changed the decor so nobody could get stuck.
Ike Book Shelf stated, block the area behind the tube so the fish cannot get stuck again, that way no second ocurance.
Hopefully he pulls through okay, if he's swimming around it sounds Iike
he just bruised himself up a bit. Give it time and see what happens.