Later, while staying in Ba Sing Se, Aang found the derelict zoo and decided, upon seeing how unhappy the animals were, to reconstruct the zoo in the Agrarian Zone. After being released, a group of hog monkeys began harassing civilians and destroying shops, before being lured outside the city and in to the new zoo by the bison whistle.
The hog monkey has a vaguely canine face, a long tail, and the body of a primate. It appears to run on its knuckles, suggesting that it is more closely related to gorillas and chimps than to monkeys, but it also has a long tail, which apes do not have. It has reddish eyes and a dog-like snout that is full of sharp teeth, including two tusks protruding from its lower jaw. Its fur is brown on most of its body, albeit the area around its face and head is of a much darker shade.
Hog monkeys commonly roam in troops or small packs. Its tusks could be for display, or killing larger prey. Due to its dog-like snout and small eyes, it probably relies more on scent than sight. Although the hog monkey does not really resemble a hog in any way, its noises are swinish in nature. It was stated that a hog monkey's bark is worse than its bite. It can, however, be soothed with leechi nuts.
Hog monkeys tend to be troublesome animals if they are let loose in a city. According to Aang, wild hog monkeys do not enjoy being ridden, but their resistance is what makes it enjoyable.
"Hog monkey" is a figure of speech used to refer to someone who tends to ramble on and on.
The fisherman says, "Well, I'll be a hog monkey's uncle." This is a play on the real-world expression, "Well, I'll be a monkey's uncle."
Aang mentions hog monkeys briefly in the unaired pilot as he asks Momo whether the lemur would save him from a pack of wild hog monkeys; the Avatar was attempting to justify his desire to save Sokka and Kya, the "only family he has", from the Fire Nation.
In the video game, hog monkeys roam in troops around a small fishing settlement and are blamed for the disappearance of food from the village.