Ripsaw Catfish
(Oxydoras niger)
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Animal Type
Fish
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Exhibits
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Range
South America
Overview
The ripsaw catfish, also known as the cuiu cuiu, is a large freshwater catfish native to South America. The species belongs to the larger group of thorny catfish, named for the spiked and hooked bony plates that line their bodies. Ouch! One thing is for sure: predators, beware.
They vary little in coloration and are usually shades of light to dark grey. Though they lack the pair of sensory barbels nearest to their nostrils that many other catfish have, they have three others at the end of their snout that come in handy when searching for food in murky water.
Ripsaw catfish, along with many other freshwater relatives, have a special internal structure that enhances their hearing. Known as the Weberian apparatus, it's a series of small bones that effectively connect the fish's swim bladder to its inner ear. Sound vibrations passing through the swim bladder transfer more easily to the ear, making the fish more sensitive to a range of noises. Given that this species often lives in rivers with poor visibility, enhanced hearing is a plus.
Hearing sounds isn't the only thing ripsaw catfish are good at—they can make them, too! They emit low rumbles by squeezing special muscles around their swim bladders, and make higher-pitched squeaks by rubbing grooved spines against notched bones in their pectoral fin joints. They've been observed making the high-pitched sound to deter or surprise predators. Their deeper growls are likely for communicating with one another, but just what each noise means is a bit of a mystery. Time to drop a hydrophone and camera into the river and hit record!
Quick Facts
Learn more about the ripsaw catfish! Did you know they migrate to reproduce? This reproductive migration takes place during the rainy season and is known as the piracema. They enter the floodplains to spawn, returning to the main rivers as the waters recede. Ripsaw catfish are one of at least 40 species to undertake this seasonal journey in the Amazon Basin.
Ripsaw catfish are found in small schools over muddy river bottoms throughout South America's Amazon, Essequibo and Sao Francisco River basins.
Ripsaw catfish eat both animals and plants. They sift through the dirt and sediment, searching for food like small crustaceans, midge or mayfly larvae, and small fish. They also eat seeds, fruit and plant matter.
Ripsaw catfish can grow to nearly 40 inches in length and weigh up to 30 pounds.
The ripsaw catfish population is considered stable. However, as a migratory species, they may be affected by things like dams and regional pollution.
Adult ripsaw catfish are well-protected due to their large size and spiny scutes. Young or juvenile individuals, though, can fall prey to carnivorous fish, fish-eating birds and reptiles like caiman.
Explore Exhibit Residents
Learn more about the animals that share an exhibit with this one.
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Emerald Tree Boa (Corallus caninus)
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White-Blotched River Stingray (Potamotrygon leopoldi)
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Giant South American River Turtle (Podocnemis expansa)
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Freshwater Angelfish (Pterophyllum scalare)
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