So my Raphael is about 5 inches now and it has some kinda wound on its side that I want to think is due to him rubbing against some of the ornaments in the tank. It looks like he chafed himself squeezing in between a ornament and the glass. Its a 20 gallon with plenty of decor and plants and he's with 5 tetras, rainbow shark, betta, rainbowfish, and a featherfin with no problems. Any suggestions??