Large parasites found protruding from fish’s head in South Atlantic. ‘The horror’

A bizarre South Atlantic fish wearing what appeared to be a big floppy hat was actually being fed on by two large parasites, marine researchers say.

The grisly discovery was made Sunday, March 2, as a team working with the Schmidt Ocean Institute explored waters 1,600 feet deep off the South Sandwich Islands. The islands are about 1,600 miles east of Argentina.

Closer inspection revealed the host was a rattail fish, which reach about 3.2 feet, and the parasites were copepods.

A remotely controlled camera lingered on the rattail fish “for the horror of it,” and one researcher called it “a new definition of a headache.”

“That poor fish,” another researcher said as a remotely operated camera lingered on the fish “for the horror part of it.”

“I hope no one is going to go to bed immediately ... I mean that just looks scary doesn’t it?” the researcher said.

Parasitic copepods are “parasitic barnacles,” though one of the researchers noted they take the shape of little “brains.”

They “attach to their hosts, potentially impacting the host’s behavior and overall health,” the Minderoo-UWA Deep-Sea Research Centre in Australia reports. They feed on tissue and blood of the hosts.

In the case of the rattail, the parasites had apparently not crippled the fish, which quickly swam away while being studied, researchers noted.

It was one of two grisly observations seen in 32-degree waters east of Montagu Island. The other was “a very unhappy octopus” covered in worm-like leeches that resembled strands of hair waving in the current.

“That’s depressing,” one researcher observed.

Montagu Island is the largest of the remote South Sandwich Islands, and the monthlong expedition expects to find undiscovered species in a largely “underexplored” region, the Schmidt Ocean Institute says.

“The science team will seek out hydrothermal vents and deep-sea volcanoes and venture into the 8000-meter-deep South Sandwich Trench, the most geographically isolated and coldest trench on Earth,” the institute says.

Ocean Census and GoSouth are collaborating with Schmidt Ocean Institute on the expedition, which began Feb. 20 and will continue through March 28.

This story was originally published March 4, 2025 at 7:23 AM with the headline "Large parasites found protruding from fish’s head in South Atlantic. ‘The horror’."