I guess he is just shy then. If he was the ruler of the tank though, and all of a sudden is hiding, something must have happen to stress him out. As for the one that died, fish do eat the bodies of dead fish if you do not remove the body fast enough.Well actually the one that died I think died because this swordtail bullied him he is 3 inches and the other one was 1.5 I think the smaller the dead one was bullied by the larger because I always saw him nipping at him and when he died his tail had a bite out of it