Eel

The eel (ウナギ, Unagi) is a unique river fish in the. It is one of only three fish (the others being the ribbon eel and moray eel) with a long and thin shadow. It is a rather expensive fish, selling for 2,000 Bells at Tom Nook's store. Like many fish, the Eel is a summer fish, and appears in the evening and night, between 4 PM and 9 AM.

In
The eel can be found swimming close to the bottom and occasionally hiding behind the rocks in the river aquarium in the first fish room.

In
The eel can be found in the right tank in the museum as a brown colored line moving across the bottom.

Trivia

 * The eel appeared in a toy set along with Purrl, a cat villager, a Koi and a fish tank.

Real-world information
The American eel, Anguilla rostrata is a fish that spawns in salt water. After hatching, the baby eels make their way to North America, on the east coast. The eels, if hungry enough, may eat their own family to survive the trip to America. They prefer to hunt at night, which is referenced by the time it appears at in Animal Crossing.