HI everyone I have my dumbo half moon male betta in a 2.5 gallon tank and he loves to swim on the bottom to go in his log and also to search for food like a piggy, I'm wondering if this is what could be tearing up his bottom fin? He has nothing that could harm him his plant is silk, his log is smooth, his moss ball is soft, and his hammock is soft. My substrate is small rocks like what you would usually see if someone uses gravel and they're topfin brand. His fins get like little slits only in the bottom and they heal up within a few days but he just does it again lol. Could this be from the gravel like I think it is?