The poisonous eel is an enemy in The Precursor Legacy. It is a lurker swimming around in the rivers of Forbidden Jungle. In the mission "Catch 200 pounds of fish", the Fisherman asked Jak and Daxter to catch two hundred pounds of good fish, but catching even one poisonous eel would spoil the whole catch, and the mission would start over.
They carry various colors similar to the jungle fish, obtaining purple, orange, and a pale brown. They have the typical lurker jaw line and leave a stream of poisoned, polluted water behind them as they swim.