I bought a couple GBR last week, one died and the other was fine. Before I left work I fed the remaining one some frozen brine shrimp and he ate fine and kept swimming around like any normal fish. After I got home from work, 7 hours later, the was no sign of him. I checked everywhere in the tank and even around it. I don't really understand where he went. Are GBR jumpers? If anyone has any clue as to what the hell happened, that would be awesome.