Classification
Though mahimahi are also known as dolphinfish, they are not related to the friendly mammals also known as dolphins. Instead, they are true bony fish belonging to the class Actinopterygii, or ray-finned fish.
Scales
Cycloid scales cover the entire body of the mahimahi. Cycloid scales have smooth outer edges and overlap from head to tail. The shape and arrangement of the scales reduce drag so that the fish swims faster.
Fins
Mahimahi have seven fins: a dorsal fin that runs the length of the body, an anal fin that lies on the underside of the fish, two pectoral fins, two pelvic fins and a forked caudal fin.