Hello, today I cam home from school to find my dojo loach swimming at the surface of the tank, which he sometimes does during a storm. He was on the bottom of the tank yesturday but today I noticed he is actually floating at the surface. His body is floating at the top, almost surfacing. But he can swim around like normal, just on top of the tank. If he stops moving he will just float. When he tries to go back down he comes back up. Any idea what's going on?