What top fin runs along a fish's back?

What top fin runs along a fish’s back? The fin is called the dorsal fin.

“Dorsal” means relating to the back, so the name describes the fin’s position. A dorsal fin is an unpaired fin located on the midline of a fish’s back. Its principal role is usually stabilization: it helps prevent the body from rolling and assists with sudden turns.

Many fish have one dorsal fin, but some species have two or three. The fin may contain bony spines, soft rays, or both, depending on the fish group. In some species, dorsal-fin spines are defensive; stonefish, for example, have venomous spines, while anglerfish modify part of the dorsal fin into a lure-bearing structure.

The dorsal fin is often confused with the anal fin because both are unpaired fins along the body’s midline. The dorsal fin is on top, whereas the anal fin is underneath, behind the anus. The tail fin at the rear is different again: it is the caudal fin and is commonly associated with propulsion.