Hmm i was thinking the same sorta thing, I had 3x silver sharks smallest was bout 8 biggest 10" and my ray is 11-12" so i took them upto work (and knocked money off ray too) how ever i have left a pair of 6" tinfoils in there and a couple of lemon barbs too, the biggest lemon is about 8-9" smallest 6". I reckon that they could potentially become food at some point but all seems well so far, they get on fairly well and keep themselves to themselves. Along with my 10" giant gourami RTGG/EEGG? (Not sure on species)