What is the fin in fishes that acts as oars?

The fins in fishes that act as oars are the pectoral fins. These fins are located on either side of the body, just behind the head. They are typically used for steering and maneuvering, but can also be used for propulsion. Pectoral fins are found in most species of fish, but are particularly important in species that live in fast-moving waters or that need to be highly maneuverable.