most likely one of the sharks or the tiger barbs.lets see. the black ghost knife two blood parrots,2 harlequins, one dwarf rainbow, 1 Congo tetra, 5 strawberry tetras, 3 Siamese algae eaters, 1 leopard pleco, 2 neons,3 rummy noses, 1 serpea tetra, 1 betta, 3 tiger barbs two green barbs,3 cherry barbs, 2 golden barbs, 1 tricolour shark, 2 rainbow sharks, 3 angel fish
here is a few pics of it
also you do not have large enough schools for most fo yuor fish, and should consider increasing them.