About 250 species of subterranean fish are known on Earth, eking out a living in a world of permanent dark and scant food. They are usually small, generally a few inches long, since there’s usually little food or prey to eat.

But in an underground chamber in northeastern India, researchers have discovered a cave fish that is much bigger—growing to nearly a foot and half in length and weighing about 10 times more than any known species.

When biologist Daniel Harries first saw the fish during a 2019 expedition, he was amazed. And perplexed.

“My first reaction upon seeing the fish myself was, I’m going to need a bigger net.”

The fish, described recently in the journal Cave and Karst Science,