Stewart’s latest work has just been published in the journalCopeia, and marks official identification of Arapaima leptosoma,the first entirely new species of arapaima since 1847.

Among the world’s largest freshwater fish, arapaimas live in tropical South America, especially Brazil and Guyana. They can grow up to 10 feet (3 meters) long and weigh 440 pounds (200 kilograms). They breathe air through a primitive lung, and tend to live in oxygen-poor backwaters.

Arapaimas have long been an important food source for Amazonian peoples. They continue to be hunted and biologists have concerns about their status, although they are not endangered.

Getting the new species named is important “because it brings attention to the diversity of arapaimas that is out there and that needs to be collected and studied,” said Stewart. “Hopefully it will get more people in Brazil looking more closely at what’s swimming around out there.”