The pectoral fins are always the first fin from the head and correspond to the arms of a land animal.

The pectoral fins can be moved in most directions: forwards, backwards and in circles. They act as a motor, brake and stabilizer. In most fish, the pectoral fins generate the moments that initiate a turning maneuver.

Fish such as Discus and Puffers use their pectoral fins for most of their motion. Typically, pectoral fins are transparent to avoid detection by predators due to their almost constant movement, continually coordinating minute directional changes and maintaining balance.

Possibly the most extreme use of propulsion by the pectoral fin can be seen in the Butterfly fish (Pantodon buchholzi) pictured below, where the fin literally acts as a wing.