The flying fishopotamus is a relatively large beast with a large build, making it an ideal creature to mount or ride. The flying fishopotamus' dark plum exterior is primarily uniform in coloration.
The creature's eyes are raised on top of its large, flattish head. Moreover, it has small ears and slit-like nostrils situated high up on the muzzle.
Its round body is relatively hairless, apart from sparse bristles on the muzzle and along the body. The flying fishopotamus has a pair of relatively large fins on its upper body. These fins are unusually long and thin, yet they are able to support the creature while it is in flight. The flying fishopotamus' lower body is lanky, resembling a fish in terms of appearance, and consists only of a long, sleek tail ending in two caudal fins.
The flying fishopotamus bears similarities to both of its namesakes. It is primarily an aquatic mammal, resembling the hippopotamus more than the flying fish. That being said, a large portion of its body is fish-like. It also bears a resemblance to the manatee. This is evidenced by Aang, who successfully mounted a flying fishopotamus without sparking a hysteric reaction from it.
Despite their apparent nature, the experience of riding flying fishopotamuses seems to trigger an adrenaline rush, as just the thought of riding a flying fishopotamus was able to trigger Aang's bending even while he was asleep.
Flying fishopotamuses seem proficient in both flight and aquatic travel and show the ability to glide over water despite their size.
- While riding a flying fishopotamus, albeit in a dream sequence, Aang referred to the experience as a waterbending rodeo.