The Fish is meant to be nimble so the rider can fit into the wave. It can have a round or hybrid nose. The lower rocker entry gives more planning surface. The shortness and width are what make a Fish.
Generally speaking, most riders prefer this board to be the same size or 3 to 4 inches taller than they are. Depending on the talent and preference of the rider, a Fish has a variety of fin possibilities. It can be a Tri Fin, Quad Fin, or a Twin Fin.