The Golden Dorado is a large species of fish native to South America. Local fishermen know it as a River Tiger.
River Monsters[]
Silent Assassin[]
The Golden Dorado first appears in the Season 3 Episode "Silent Assassin", where Jeremy Wade is tracking a monster stingray know as the Short Tailed River Stingray. He accidentally brings up a dorado before he hooks into the ray.
River of Blood[]
The Golden Dorado also appears in Season 6 in the episode, "River of Blood" where Jeremy is once again tracking in on Argentina's remote Parana River.
Mysterious reports of attacks and of some "River Tiger" brought Jeremy to the Estoros del Ibera marshes, where he caught a small Golden Dorado. He immediately suspected it was the river tiger, and his boatman confirmed this. However, the fact that the particular season was winter meant that Jeremy had to go to a different place to catch a larger dorado. Although the Parana originates farther North, around the Amazon basin, it extends well beyond the tropics, in a temperate climate, so it has relatively cold winters, which cause some smaller fish to migrate, forcing the dorado to follow.

Small Golden Dorado in the Esteros del Ibera marshes
However, Salto Grande Dam blocks prey from moving, and the dorado have enough food here regardless of the temperature. So, Jeremy heads to the dam, but the Dorado prove to be hard to catch. It takes Jeremy a few attempts to fully hook one. Once this is achieved, a long struggle ensues, after which Jeremy brings in a larger, 40-odd pound specimen.
Description[]
The Golden Dorado are notable for its very bright orange-golden color. The largest recorded individual was close to 70 pounds in weight, making it one of the apex predators of the region. Their jaws are also very notable for their powerful bulldog-like appearance.