Suckermouth Catfish

Ancistrus cirrhosus and Baryancistrus xanthellus

A bony-plated South American catfish, also called a plecostomus or 'janitor fish,' that scrapes algae with its sucker mouth.

🐟 Fish

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About the Suckermouth Catfish

Suckermouth catfish, often called plecostomus, can grow to 20 inches long. They may be sandy with black spots or dusky brown, and their bodies are covered in bony plates. They live in fast streams and rivers with pebbly bottoms in South America, from the Guianas and Venezuela to the Río de la Plata. They eat algae, plants, invertebrates and small fish.^[1]

Quick facts

Scientific name: Ancistrus cirrhosus and Baryancistrus xanthellus^[1]
Size: Up to 20 inches long.^[1]
Lifespan: 10 to 15 years on average.^[1]
Diet: Omnivore. Algae, plants, invertebrates and small fish.^[1]
Habitat: Fast-flowing streams and rivers with pebbly bottoms.^[1]
Where it lives: South America, from the Guianas and Venezuela to the Río de la Plata.^[1]
Group life: Mostly nocturnal.^[1]
Babies: Eggs laid in tunnels or caves; males guard them.^[1]
Conservation status: Least Concern for Ancistrus cirrhosus (IUCN Red List, assessed 2020).^[2]

Fun facts

Aquarium keepers call them 'janitor fish.'^[1]
Fathers guard the eggs.^[1]
They rest in dark cracks during the day.^[1]

Vocabulary

fish: A cold-blooded animal that lives in water, breathes with gills and usually has fins and scales.
oviparous: Laying eggs that hatch outside the mother's body.
algae: Simple plant-like living things that grow in water.
nocturnal: Active mainly at night.
least concern: A conservation label meaning a species is widespread and not at risk of dying out soon.

See it in person

Smithsonian's National ZooWashington, D.C. · AmazoniaSee this animal on the zoo's website ↗

These zoos had this animal when we gathered our information, but animals sometimes move. Check the zoo's website or contact the zoo before you visit.

Sources

[1] Smithsonian's National Zoo & Conservation Biology Institute. “Suckermouth catfish.” https://nationalzoo.si.edu/animals/suckermouth-catfish (accessed 2026-10-08)
[2] IUCN Red List of Threatened Species. “Ancistrus cirrhosus.” https://www.iucnredlist.org/species/49830571/164512524 (accessed 2026-10-08)

Facts last checked 2026-10-08.

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