I was taking pictures this afternoon of the tank that I just changed the sand in two days ago. I realized that I was missing a fish. I probed the tank to no avail and then started looking on the floor. He was under the back of the stand (black iron stand), dried up but still with his color. I know he was in there this morning when I fed them. The only place he could have gotten out was a spot on the back where the HOB filter goes in. It is about 3/4" wide and 6" long. I believe this may be the same one that jumped out last week when I had the lid open to do some maintanence. He also was swimming wildly around the top one other day last week. Other than those times, he appeared to be perfectly normal. I don't know what prompted the strange behavior that eventually let to him finding the floor.