Oyster

The Oyster is a fish that can be found underwater. It appears all day from September to February. When selling it to Re-Tail, the player will earn 400 Bells.

Location
The Oyster is found in underwater in the ocean. Its shadow is small and it does not move.

The Museum
The Oyster can be donated to the museum. Upon doing so, the following text is given by Blathers:

"Oysters are sometimes referred to as "the milk of the sea" because of their high nutritional value. Young oysters come from eggs, attach themselves to hard places in the ocean, and then grow. They can change gender, allowing them to reproduce regardless of their neighbors' genders."

Quote
Upon catching the fish, the player will say the following:

"I got an oyster! He's been a bit too shellfish."