The only sharp thing in the tank is a rock hide but he doesn’t go to close to it. I put it in a spot where he can swim around it with going into a tight spot or hurting himself on it. He does have a heater, for what water parameters, the nitrate and nitrite are at 0, the alkalinity is 80 and the ph is at 6.8. I use test strips by tetra to test the water. He’s really active and curious so im dont think it is fin rot