There are many mysteries about the Amazon River. However, researchers uncovered an almost two-century-old secret when discovering a new species of piranha-like fish.

Unmasking the Fish

The pacu is a close relative to the piranha with human-like teeth.

For almost 200 years, a type of piranha has secretly disguised itself as another nearly identical species. The newly identified fish, Myloplus sauron, is a pacu, a close relative to the piranha. Researchers named the species after the dark lord Sauron from “Lord of the Ring.” However, the fish isn’t as sinister as the villain. M. sauron is often confused with the iconic freshwater piranha or M. schomburgkii. Unlike the fictional villain, the newly discovered species is less bloodthirsty and has a mostly vegetation diet. The M. schomburgkii was first discovered in 1841 but is largely ignored by scientists today.

Researchers discovered the species and two others during an effort to clear up confusion surrounding piranhas and their relatives. In addition, they wanted to better understand the fish in and around the Amazon River. The new species is not named after the Lord of the Rings villain for its viciousness but rather its markings. On its side, there is a black line resembling the dark lord Sauron’s eye.

“Its pattern looks a lot like the Eye of Sauron, especially with the orange patches on its body,” study co-author Rupert Collins, the senior curator of fishes at the Natural History Museum in London, said in a statement. “As soon as one of my colleagues came up with the name for this fish, we knew it was perfect for it.”

M. sauron joins a list of creatures named after the literary villain, including a dinosaur, a frog and a group of butterflies.


Understanding the Piranha

Not all piranhas are meat eaters; some only eat vegetables and fruit.

According to researchers, Piranhas have a bad reputation for being a bloodthirsty fish, but that isn’t the case. The fish are infamous for being a savage creature that can devour a human or animal in seconds. But their reputation isn’t all that true. While they are known to bite, they are far less aggressive than we think. “The former US President Teddy Roosevelt is responsible for much of the piranhas’ reputation,” Rupert said. “He wrote about a cow being torn apart in front of him during a visit to South America, cementing their ferocious image in the public consciousness.”

Rupert said the piranhas were rounded up in nets and starved, which drove them into a feeding frenzy before pushing the cow into the water. “Generally, the fish will only attack like this when they are very hungry or defending their nests.”

Different Piranhas

Many species, commonly called piranhas, don’t eat meat at all. Pacus are closely related to piranhas; however, they lack sharp teeth because they consume plants and fruit. Instead, their teeth look a lot like human teeth. They are dull to break down their vegetarian diet. There are over 100 species in Serrasalmidae, the family containing piranha and pacu. Even for experts, it’s tough to tell each and every one apart and their relationship.

“Many species were established using differences in teeth, but similar teeth have popped up repeatedly in distantly related fish,” Rupert explains. “They can also look very different at every stage of their life, with one species containing animals with many appearances.”

Until recently, researchers could confidently identify the Myloplus schomburgkii in rivers across South America because of the black band down its side. However, recent research suggests that it’s not one species but three.