I have one of these, its a pure beast of a goby. Ours is currently around 6 inches in length and very wide in girth (hense their common name of Fat sleaper goby) and is a very aggressive eater. It rarely stops eating ever, picking algea from the walls and decor in the tank inbetween feeding times when it will eat anything from lettuce and pellets to whole whitebait and mussel/cockle, smaller fish are not safe with them, i have also seen it filter feed like a dragon goby when small particals of food are in the water using its huge mouth to draw in large gulps of water. We keep ours in brackish water (SG 1.012) with other large brackish fish (scats, monos, archers, morays and shark cats).