I have a commmon pleco that seems to be having problems staying on the bottom. He seems to be feeding normally and I sometimes find him on the glass. When I feed the fish, he starts going for the bottom to feed and keeps floating up to the surface and seems to be working to stay down. Then he will swim into the plants and rest. I think he may be using the heavy growth to keep himself down. Hes about 7 inches long in a 135 gallon planted tank. Any Ideas? I may be worrying about nothing, I dont know. Thanks