Chuck a line into the Amazon river and you might expect to pull out a piranha or two. What you wouldn’t expect is a giant, air-breathing monster-fish that can grow to twice the length of an adult human.

The paiche, also known as arapaima or pirarucu, is one of the largest freshwater fish in the world. Fully grown, it can reach seven feet or more, with some specimens stretching to an impressive 15 feet from tip to tail. Weight-wise, paiche can reach anywhere from 200 to 400 pounds.

The paiche’s size isn’t its only notable characteristic. This fish has been around for a long, long time. So long, in fact, that it’s considered a living fossil, whose actual oldest fossil dates back to the Miocene Epoch (which ranged from 5.3 million to 23 million years ago).

This prehistoric relic has some strange traits, including the need to surface for air. In addition to gills, the fish has an organ with lung-like characteristics. The ability to breathe air is helpful in the oxygen-deprived waters of the Amazon basin, but leaves the paiche vulnerable. When the fish surfaces, it often sucks in air with a loud, distinctive gulp that local fishermen can identify from some distance away, making the paiche easy to catch. Amazonian fishermen have long prized the fish for its large size and tasty meat, netting or spearing it in such large numbers that its future was in doubt by the beginning of the 21st century.

Thankfully, conservation and reintroduction efforts, combined with a large increase in farmed paiche, have ensured that this ancient fish will not disappear anytime soon. And that’s a great thing for Amazonian cuisine, as paiche is an incredibly tasty and meaty fish, with a firm fillet that stays succulent in most preparations, whether roasted, grilled, or steamed. It’s also a fantastic fish for ceviche. A fresh ceviche de paiche in the city of Iquitos rivals the best ceviches along Peru’s Pacific coastline.