Lionfish have an orange oval shaped body with a mouth and white teeth. Above that are the Lionfish's eyes and eyebrows. On the belly of the lionfish are brown stripes, below that being average sized fins.
Above the lionfish, on its head are three other fins, only bigger than the ones on the bottom. Visible on its body is a large fin, which it uses for movement. Attached to its tail are two fins highly resembling the fin on its body.
Lionfish will swim horizontally when the player isn't around. Often times one or two are found in a single area. Lionfish are very territorial, as they will viciously chase the player until they leave the area. Sometimes they are placed in crowded areas, making them hard to avoid and the player prone to damage.
They can be killed with three bombs, a rather high number. They are difficult to kill as they always chase the player, the easiest way to bomb them being to move vertically and lay a bomb. They leave an emerald once killed. Lionfish do not attack other enemies, and if necessary, go through them to get to the player.