I have a 55 gal freshwater tank with 2 Gouarami's, 3 Bala sharks, 2 algae eaters and a clown Plecko. When I woke up this morning both algae eaters had buried their heads in the rocks and died. I found them in the tank just sticking tail up, heads fully under the rocks. What could be a reason for them doing this? If it was just one I wouldn't be so worried but since both did it, I'm a little worried for the other fish in the tank. Any hypotheses as to why they would do this?