Two-headed fish

"fire"

- What? You get more for your money that way.

The two-headed fish lived in the Jang Hui River, near the Fire Nation lake settlement of Jang Hui. A neighboring Fire Nation factory polluted the river by dumping its sludge refuse into the water, resulting in vast ecological damage to the surrounding area including to the fish, the wildlife, and the village's inhabitants themselves. It was this pollution that caused the fish to mutate into having two heads.

History
When Team Avatar arrived at this poor village, Katara was saddened by the hardship of the villagers. She fed Appa some purple berries to give him the appearance of sickness, forcing the group to stay a few days longer. The team went to town to buy more supplies and it was there that Xu offered Sokka a choice between a one-headed and a two-headed fish. Sokka chose for the latter, stating that "you get more for your money that way." This statement caused the rest of the gang to run away in disgust.

Trivia

 * Polycephaly is a condition of having more than one head and is derived from the stems poly- meaning "many", and cephal- meaning "head." This encompasses bicephaly and dicephaly (both referring to two-headedness). Each head of a polycephalic animal has its own brain, and so they share control of the organs and limbs, though the specific structure of the connections varies. Animals often move in a disoriented and dizzy fashion, with the brains "arguing" with each other; some animals simply zig-zag without getting anywhere. A severe example of this behavior is a two headed snake that may attack and even attempt to swallow the other head. Polycephalic animals survive poorly in the wild compared to monocephalic animals.