FLYING FISH, the name generally given to fishes of the genus Exocoetus, in which the pectoral fins are greatly enlarged. The lower lobe of the caudal fin is very long and, with strong strokes of the tail, these fishes emerge rapidly from the water and, with the pectoral fins outspread, sail through the air at a great speed, for distances up to 200 yards. It is probable that the flight is an effort to escape from large piscivorous fishes, such as bonitos. There are numerous species of Exocoetus, all from warm seas.
The so-called flying gurnards (Dactylopterus) are not related to the flying fishes. They have relatively larger pectoral fins than Exocoetus, but appear to be less efficient fliers, perhaps because the caudal fin lacks the long lower lobe. There are three or four species from tropical seas.
Pantodon, a little African fresh-water fish, has large pectoral fins and is said to fly; but perhaps the most interesting flier is Gastropelecus, a Characin of the rivers of South America, a deep-bodied fish with a large rounded, sharp-edged ventral keel, formed by the greatly expanded coracoid bones, which serve for the attachment of the enormous muscles of the pectoral fins. This fish has been seen by Eigenmann to progress by rapid beats of the strong pectoral fins, with the keel just cutting the surface of the water, and finally to emerge in a true, but not prolonged, flight.
The Catalina flying fish (Cypsilurus californicus) of southern California waters, sometimes 18 in. long, one of the largest known species, is a strong flier, with enlarged ventral as well as dorsal fins.