Mine recently died and here's what I know. It was 7 1/4" long and an all around good fish. It was a picky eater and would not touch pellets (tried like crazy to get it to eat them), went crazy for earth worms and small krill...wouldn't touch the big ones. Like what was mentioned earlier in this post, it liked stuff that moved and wouldn't bother stuff that was not moving (like dead worms on bottom of tank or anything floating stationary). It did try a small block of freeze dried tubifex worms once and only once. I suspect that it would eat a feeder guppy or two on occation but I personally never saw it happen...I did see it stalk them. It knew when you entered the room and would come to the top and beg for a nibble...it was not a piggy eater...two or three small krill and it was done. It would mostly stay to itself and never caused trouble with anyone but would interact with some other fish of similar size. I miss my "little" buddy.