Flying dolphin fish

The flying dolphin fish is a predominantly aquatic mammal found in Fire Nation waters and sought out as a form of recreation.

History
While escorting Zuko and his family back to the Fire Nation mainland, Avatar Aang and Kiyi decided to ride on a flying dolphin fish, much to the amusement of the other members of Team Avatar. Despite Katara's invitation, Sokka refused to mount one of the creatures, stating that he preferred his rides to be mechanical. Alarmed over Kiyi riding on top of a wild creature, Ursa beckoned the two to return to the Fire Nation cruiser, where Aang apologized and reassured her that flying dolphin fishes are "among the gentlest creatures in the world.

Anatomy
The flying dolphin fish is a relatively large mammal with a strong build, making it an ideal creature to mount or ride. Individuals bear a distinct coloration pattern, with a predominantly dark gray dorsal half and a white underside to produce countershading typical in many marine creatures. A light gray strip also runs near the creature's lateral line, beginning from the base of the rostrum and ending near the caudal peduncle.

The rostrum, absence of hair, and the general shape of the flying dolphin fish all contribute to streamlining the body in order to reduce drag in the water. Flying dolphin fishes have a pair of elongated pectoral fins, a dorsal fin, and a homocercal caudal fin, all of which are translucent and light gray in coloration. The pectoral fins are supported by a significant basal component to aid in movement when gliding out of the water, while the dorsal fin is strengthened by a singular spine near the origin. These elements allow the flying dolphin fish to jump up several feet above the water surface for a short period of time.

Behavior
Flying dolphin fishes have a calm temperament, making them ideal for mounting or riding. This gentle nature also allows the creatures to interact closely with humans with little difficulty, as they have been observed flanking a cruiser near the surface of the water. Typically found in open waters, flying dolphin fishes prefer to travel in small pods.

Connection
The flying dolphin fish bears most structural resemblance to several members of Delphinidae, consisting of all known oceanic dolphins, particularly with regards to its body shape and coloration. However, the flying dolphin fish also bears close resemblance to members of Exocoetidae in terms of its fin structure and distribution, as those are more characteristic of flying fishes.

Trivia

 * The flying dolphin fish has no apparent breathing structure in place, as it lacks the blowholes seen in dolphins and gills seen in flying fishes.