Pike

The Pike is an uncommon river fish in the introduced in. It is a large, green-yellow fish with white spots and yellow fins, and it is available from Fall to early Winter.

In
Blathers will comment on the player's donation as follows:

It can be found in the middle-right tank in the Aquarium exhibit.

In
Once donated to the museum, the Pike can be found in the recessed fish tank in the first fish room with the Snapping Turtle and Koi.

Real-world information
The Esox Lucius, or Northern Pike, is one of the two living species of the Esox family; the other one being the Muskellunge or Musky. They can live up to 30 years of age. A pike's diet consists mainly of small shoal fish, insects, amphibians, and small mammals (such as moles and mice). Even small or young birds can be a target. They have also been known to be cannibalistic, sometimes feeding on smaller pike. Pike can be found in North America and Europe.