if you have corals then dont put this one into your tan as the best looking slugs feed from "specific hard corals, soft corals, gorgonians, anemones, sponges and other inverts" i think that a five gallon tank may be too unsuitable for these things but again it depends on what you have in the tank, if it gets attacked say goodbye to everything cos the book sitting infront of me says they release poison dye from a galnd in the mantle.