Loach

The Loach is a river fish in the introduced in.

Donating to the museum
The Loach can be donated to the museum by talking to Blathers. During the donation, Blathers will say the following about the Loach:

In
The Loach can be found in the leftmost tank of the freshwater fish room.

In
The Loach can be found in the recessed tank in the freshwater room in the aquarium with the Catfish and Bluegill.

Real-world information
It is unclear what type of loach appears in Animal Crossing, since there are vast varieties of loaches. It is, however, a member of the Cobitidae family of loaches, called the True Loaches, which live in fast flowing waters. All true loaches are "bottom feeders," meaning they swim at the bottom of rivers and tanks eating the algae at the bottom. They also eat small crustaceans and insects, but only during the day. Under true loaches, it can be a horse-face loach which grows to roughly 20 cm (8 inch). This type of loach is a private and public aquarium favorite because of its eating habit which cleans a tank for the owner, making it easier to keep fish.