A search for a fish lost to extinction led to a brand-new species hiding in a South African river.

Researchers identified a new freshwater fish species in South Africa after years of genetic testing and analysis.

In the canals, marshes, and swamps of the Florida Everglades, invasive fish are silently slipping into new waterways. Among them are the Asian swamp eel and the bullseye snakehead, two air-breathing ...

This eerie, bulging-eyed fish lived beneath Antarctic ice for centuries - and scientists only just realized it's a new species.