Which freshwater fish is famous for having eyes divided into upper and lower halves?

The four-eyed fish is famous for having eyes divided into upper and lower halves.

This unusual arrangement belongs to the genus Anableps, especially Anableps anableps. The fish usually swims at the surface, with the upper half of each eye looking through the air and the lower half looking through the water. A special horizontal division in the lens helps each portion focus in its own environment.

Despite its name, the fish has two eyes, not four separate eyes. The name describes the four visual fields created by the divided eyes. Four-eyed fish live mainly in slow-moving freshwater and brackish coastal habitats of tropical Central and South America, where surface feeding is common.