This morning when I went to feed the fish I noticed that my fire fish was nowhere to be seen. I looked all over the tank moving rocks and sand. Only to find him on the floor dried up. Must have jumped out. How do I prevent other fish from suffering the same fate? The tank has a number of openings on the top but the two rear ones I cover with plastic panel. There are 2 openings under my lights that i leave open so that I do not get a green house effect. Any ideas?