The rainforest-flanked rivers of tropical South America hold six more species of catfish than previously thought, new research suggests. But these aren’t the wide-mouthed, whiskered catfish you may be familiar with from murky waterways throughout the U.S. interior. The new fishes look like something out of a D&D Monster Manual: sucker-mouthed, adorned in armor plating, and with defensive spines jutting out from their heads. Oh, and the males have snouts carpeted in squiggly tentacles.
These splendidly strange fish—all in the genus Ancistrus—are known as “bristlenose catfish.” There were already dozens of species of bristlenose catfish known, some of which are commonly kept in freshwater aquaria as tank-cleaning “algae-eaters.” Most of the bristlenoses are found in South America and Panama, and in particular the Guiana Shield, a region of ancient highlands in northeastern South America that’s home to lush forests, tabletop mountains, and spectacular waterfalls. Skirting the Guiana Shield are the Orinoco and Amazon River basins, where the new catfish make their home.
A research team led by Chicago Field Museum conservation biologist and ichthyologist Lesley de Souza discovered the new species while examining museum specimens of Ancistrus catfish from the Guiana Shield region. The goal was to iron out some of the relationships between known species and to verify species identities in more nebulous cases. But after taking detailed measurements of the preserved catfishes’ physical features and analyzing their DNA, de Souza and her team didn’t just validate the existence of five known species, they identified six totally new ones.
The new catfishes, described in a paper published today in the journal Zootaxa, can be distinguished from other bristlenose catfishes through a number of features. One new species is covered in tiny white dots, with a noticeable “saddle” pattern on its back. Another has males that sport a particularly short beard of tentacles. Many of the new species’ names reflect something about the biology of bristlenose catfishes, including their uncommonly determined parenting. Bristlenose catfish fathers, which defend nests of eggs from would-be predators using their sharp facial spines, were honored for these labors are honored in a name that would make any Harry Potter fan do a double-take: Ancistrus patronus, where “patronus” is Latin for “protector.”
The attentiveness of Ancistrus fathers to their young is thought to be wrapped up in the evolution of those weird-ass face tentacles that are so pronounced in males. Even after the eggs hatch into a bunch of wormy, wriggly fry, they stick around in the safety of dad’s shadow until they absorb the rest of their yolk sacs. It’s thought that females on the hunt for a mate would be smitten by the sight of a male already caring for a gaggle of fish babies. If looking like a Cthulhu-salmon hybrid makes you a 10 in the catfish dating scene, so be it.
Bristlenose catfish thrive in fast-flowing streams, and are incredibly sensitive to changes in their environment. Deforestation and agriculture are familiar threats to Amazon species like these, but the catfish are also threatened by gold mining in the region. Gold miners employ a process that uses mercury to pull gold from the river, polluting the waterway with the toxic element. This, combined with the muddying of the river from dredging, is decidedly not awesome for the catfish, but perhaps even worse for species that depend on catfish for food.
“Giant river otters love to eat these catfish, and jaguars have been observed to have higher mercury levels from eating contaminated fish or other species that feed on fish,” says de Souza in a statement. “This can have dire impacts on the whole ecosystem. All the layers of the Amazon basin are interconnected from the rivers to the forest canopy.”
For now, a huge step towards the long-term survival of these new catfish is the simple act of naming and describing them, says de Souza. Once you know how many species there are and where, you can get a grip on their biology, behavior, and conservation needs.
The Amazon and Guiana Shield together have spellbinding levels of diversity—estimated well over a third of all the plants and animals on Earth. With discoveries like this, it’s clear there is still plenty of life that’s hidden, and unfortunately, plenty that can be lost forever.