Ripsaw catfish

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Onglets

Description

Distinguishing features

This large tropical fish lives in the rivers of South America, notably in the Amazon basin and the Paraná and Paraguay river basins. Its colour varies from dark brown to anthracite black.

Its body has lateral bony scales with thorny projections that serve as protection. These integumentary structures are the origin of its name, “ripsaw”.

The ripsaw catfish is the largest catfish in the Doradidae family. It has a long snout with a downward facing mouth and three pairs of sensory barbels that it uses to find food in muddy and sandy substrates. It has a robust, spiny dorsal fin.

Reproduction

There isn’t much information on the reproduction of ripsaw catfish in the wild, mainly because they live in deep, often murky waters. We do know that they migrate each year to plains and floodplain forest areas during the annual floods to reproduce.

Ripsaw catfish reach sexual maturity at roughly 50 cm long.

A female can lay up to 250,000 eggs, which are quickly fertilized by a male. Once hatched, the young catfish swim away and mature in flooded vegetated areas, which are rich in microorganisms.

Diet

Ripsaw catfish are benthic omnivores that forage for food in sediments. Their mouth and barbels are designed to help them search through muddy and sandy riverbeds.

Ripsaw catfish digest slowly, which allows them to easily ingest a large variety of food. They eat by sucking up organic debris and invertebrates (mainly insect larvae) from riverbed sediments in large rivers. They also eat fruit and seeds that have fallen into the water when available.

Predators

Adults, who can sometimes grow to be longer than a meter, have few natural predators. Before reaching that size, they sometimes fall prey to large carnivorous fish in the Amazon, such as the Arapaima (Arapaima gigas).

Young ripsaw catfish are vulnerable to predators from the family Cichlidae, such as the yellow peacock bass, fish-eating birds (herons, cormorants, and anhingas), and aquatic reptiles (notably broad-snouted caimans).

Ripsaw catfish is known for its delicious flavour. The colour of its flesh is similar to that of salmon. It is a very important fish in Amazonian markets.

Habitat

Ripsaw catfish prefer deep, murky water with a slow to medium current. They are most commonly found in the channels of waterways, but during the rainy season they can also be found in lakes and flooded forest areas.

After the rainy season, the fish begin a return migration, a journey which can span up to 400 km.

Ecology, behaviour

Ripsaw catfish are efficient benthic foragers, helping recycle organic matter and stir up sediment. They can also produce noise by vibrating their pectoral spines and their swim bladders to communicate with other ripsaw catfish.

Seasonal migration based on the water cycle is vital to ripsaw catfish reproduction. Hydroelectric dams in the Amazon impact their migration. Thankfully, some of the large dams in the Amazon, like the dam on the Madeira River, have built deviated canal systems that allow ripsaw catfish to pass through and continue along their migration route.

French name

Oxydoras noir

Scientific name

Oxydoras niger

Phylum

Chordata

Class

Osteichthyes (bony fish)

Order

Siluriformes

Family

Doradidae

Size

Up to 120 cm

Weight

Up to 20 kg

Status

Stable

At the Biodôme

There are two ripsaw catfish in the capybara pond, in the tropical rainforest ecosystem. They share the pond with other large fish such as the tambaqui, the tiger catfish, and the tropical gar. They are distinguishable by the barbels on their inferior mouths and the bony scales that are clearly visible on their sides.

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