SFE is too small, you'd see evidence in his body if he did. Crabs are possible, they can clean up quite a bit. Think of the last time you saw your angel and when you broke the tank down.... Odds are it died from whatever and the crabs had enough time to dispose of his remains. ALSO, it is possible that the fish jumped out and another pet consumed him. Have you completely checked the "flop zone" around the tank?
In any case, the fish is gone....sorry.