Devonencus

The Devonencus (デボネンクス, Debonenkus) is a species of ancient fish briefly appeared in Ponyo.

About
It is rather a large species with flattered appearance.

As its name suggests, it thrived during the Devonian period.

Trivia

 * It is an imaginary species created by Hayao Miyazaki.
 * Its appearance was based on two of largest fish, whale shark and Leedsichthys, and a yokai called Ittan-Momen.