A
Species Profile

Armored Catfish

Loricariidae

Armored grazers of the Americas
Endless luck/Shutterstock.com

Armored Catfish Distribution

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Invasive Species

This map shows coastal regions where Armored Catfish are found.

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Aquarium Fish Bushymouth catfish (Ancistrus dolichopterus). Ancistrus dolichopterus, one of the Ancistrus species called the Bushymouth catfish, is a species of armored catfish native to Brazil.

At a Glance

Family Overview This page covers the Armored Catfish family as a group. Stats below are general traits shared across the family.
Also Known As Suckermouth catfish, Suckerfish, Algae eater, Cascudo (Brazilian Portuguese), Cascudo (Spanish)
Diet Omnivore
Activity Nocturnal+
Lifespan 10 years
Weight 8 lbs
Status Not Evaluated
Did You Know?

Loricariidae is one of the largest catfish families, spanning many body shapes-from tiny algae grazers to meter-class giants.

Scientific Classification

Family Overview "Armored Catfish" is not a single species but represents an entire family containing multiple species.

Loricariidae (suckermouth armored catfishes) are Neotropical catfishes characterized by rows of bony dermal plates (‘armor’) and a ventral oral disc adapted for clinging and scraping. Many are algae- and detritus-grazers and are popular in aquaria as “plecos.”

Kingdom
Animalia
Phylum
Chordata
Class
Actinopterygii
Order
Siluriformes
Family
Loricariidae

Distinguishing Features

  • Bony lateral and dorsal armor plates rather than typical scalation
  • Ventral suckermouth with scraping teeth; adapted to cling to substrates
  • Often flattened underside and strong pectoral fins for station-holding in currents
  • Great diversity of body forms (e.g., bristlenose, whiptail, bulldog/‘rubbernose’)

Physical Measurements

Males and females differ in size

Length
8 in (1 in – 3 ft 3 in)
6 in (1 in – 2 ft)
Weight
0 lbs (0 lbs – 13 lbs)
0 lbs (0 lbs – 7 lbs)
Top Speed
6 mph
short bursts 3–10 km/h

Appearance

Primary Colors
Skin Type Armored freshwater catfish (Loricariidae) with rows of bony plates and a belly suckermouth. Skin has odontodes (tooth-like spines), often larger on head, ridges, and fins; armor varies.
Distinctive Features
  • Identity/generalization: Loricariidae ('plecos', suckermouth armored catfishes) are Neotropical freshwater fishes characterized by bony armor plates plus a ventral oral suction disc used to adhere to surfaces and graze/scrape.
  • Body plan: dorsoventrally flattened to moderately depressed body; broad head; ventral mouth; many have an enlarged dorsal fin and strong pectoral fin spines for bracing in current.
  • Armored catfish (Loricariidae, plecos) vary a lot in size: some are about 2.5–4 cm long, while the largest reach around 70–100+ cm. Don't assume all plecos are big.
  • Coloration/pattern: predominantly cryptic earth tones (brown/gray/black/tan/cream) with frequent spots/stripes/mottling; vivid accent colors occur in a minority of species and are overrepresented in the aquarium trade relative to wild diversity.
  • Armor/texture: scutes form longitudinal rows; surfaces may be smooth to strongly keeled; odontodes can give a sandpapery feel and may form cheek/fin bristles in some taxa.
  • Many armored catfish (Loricariidae) are benthic periphyton and detritus grazers or scrapers on rocks, wood, and submerged surfaces, but diets vary from wood‑eating to insect‑eating, eating both plants and animals, or algae‑eating.
  • Behavior (generalization with variation): often nocturnal/crepuscular and shelter-oriented (crevices, caves, under wood), but some are active by day; many are strongly rheophilic (adapted to fast-flowing streams/rapids) while others prefer slower rivers, floodplains, or vegetated margins.
  • Reproduction (broad trend): many species show substrate/cavity spawning with some level of guarding-often by males-though exact breeding behaviors vary substantially across genera.
  • Armored catfish (plecos): small species live about 3–8 years, while larger plecos often reach 10–20+ years. In tanks some big species may live 20–30 years; lifespan varies by species and care.
  • Distribution: native to Neotropical freshwaters (Central and South America), occupying diverse river basins and habitats; not marine.
  • Aquarium relevance and invasive potential: many Loricariidae are popular 'algae-eater' aquarium fishes; some large, hardy species (notably certain 'sailfin'/'common pleco' types) have established invasive populations when released, with potential bank-burrowing and ecosystem impacts.

Sexual Dimorphism

Sexual dimorphism occurs in many Loricariidae but is not uniform across the family. Differences are often subtle outside breeding condition and can be lineage-specific.

  • More developed odontodes/bristles in certain groups (e.g., on cheeks, pectoral fin spines, or along the body), especially during breeding condition.
  • Often a broader head and thicker pectoral fin spines in some taxa; males may appear more angular.
  • Genital papilla shape/position differences are used for sexing in some species (varies by genus).
  • Frequently rounder/deeper body when gravid (egg-bearing), with a comparatively smoother appearance if males develop prominent odontodes.
  • In some taxa, females have less pronounced cheek/pectoral odontodes and a comparatively narrower head.

Did You Know?

Loricariidae is one of the largest catfish families, spanning many body shapes-from tiny algae grazers to meter-class giants.

Their "armor" is made of bony dermal plates (scutes) arranged in rows, giving protection and reducing predation risk.

The ventral oral disc lets many species cling to rocks and wood in strong currents while scraping periphyton (algae + microbes).

Diet varies widely: many graze algae/detritus, some specialize on biofilm, and some (e.g., Panaque and relatives) are famous for wood-eating habits.

Many species show male parental care-eggs are laid in a cavity or burrow, and the guarding parent fans and protects them.

Several genera in the aquarium trade are routinely mislabeled as "common plecos," and adults can outgrow typical home tanks.

Introduced "sailfin/common plecos" (often Pterygoplichthys spp.) have established wild populations outside the Americas, where burrowing and competition can impact native ecosystems.

Unique Adaptations

  • Bony dermal plates ("armor") covering most of the body, combined with stout fin spines that can lock for defense.
  • Suckermouth oral disc and flexible lips that seal to substrates-useful for station-holding in currents and for scraping food films.
  • Tooth specializations: many have teeth suited for rasping algae/biofilm; others have robust teeth for gouging wood or processing tougher plant material.
  • Odontodes (dermal teeth) that can be enlarged on cheeks, body, and fins for defense, combat, and sometimes sex-specific ornamentation.
  • Digestive and microbial adaptations in some lineages associated with wood-rich diets; many still rely heavily on biofilms growing on wood rather than "wood" alone.
  • Accessory respiration is present in several groups (various mechanisms across taxa), supporting survival in warm, low-oxygen waters-especially in sluggish habitats.

Interesting Behaviors

  • Clinging and grazing: many species attach to rocks/wood and rasp periphyton with spoon- or comb-like teeth; intensity and food choice vary by genus and habitat.
  • Mostly crepuscular/nocturnal activity is common, but some species forage openly by day in shaded or high-flow habitats.
  • Cavity and burrow spawning is widespread: adults (often males) guard eggs/larvae in hollow logs, rock crevices, or excavated banks; details differ among lineages.
  • Territorial displays: many use cheek odontodes (spiny, extendable bristles) and fin-spine postures in disputes-especially among Ancistrini and related groups.
  • Seasonal movements: in floodplain systems, some shift between main channels and inundated forests/shallows as water levels rise and fall.
  • Habitat breadth with extremes: across the family are rheophilic (fast-water) specialists, quiet-water detritivores, and even cave-adapted species with reduced eyes/pigment (in a few lineages).

Cultural Significance

Loricariidae (plecos) are well known in the aquarium trade as algae and detritus grazers, but many grow large and need special care, affecting aquarium ethics. In tropical South America they are eaten. Introduced burrowing Pterygoplichthys can be nuisance "devil fish" that spur fishing, news, and control efforts.

Myths & Legends

Name-and-nickname traditions: in parts of Mexico and Central America, invasive sailfin/common plecos (often Pterygoplichthys) are popularly dubbed "devil fish," a modern folk label tied to their armored look, spines, and persistence in altered waterways.

Aquarium-era origin story: "pleco" became a widespread hobbyist name from the old catch-all genus Plecostomus, a historical naming legacy that persists even as taxonomy split the group into many genera.

River-life anecdotes in Amazonia: regional vernacular names in Portuguese- and Spanish-speaking areas often emphasize the fish's armored nature and have entered local storytelling and everyday speech about "hard-shelled" river fish.

Conservation Status

NE Not Evaluated

Has not yet been evaluated against the criteria.

Population Unknown

You might be looking for:

Corydoras catfish (armored catfish)

32%

Corydoradinae (family Callichthyidae)

Often called “armored catfish” in aquaria; small bottom-dwellers with bony plates, but lacking the pleco-style suckermouth.

Bristlenose pleco

26%

Ancistrus sp.

Very common aquarium ‘armored catfish’/pleco; small loricariid with facial bristles (esp. males).

Sailfin pleco

18%

Pterygoplichthys sp.

Large loricariids with tall dorsal fins; widely introduced/invasive in many regions.

Common pleco

14%

Hypostomus plecostomus

Classic ‘pleco’ in the aquarium trade; a loricariid often (sometimes incorrectly) labeled as the common pleco.

Life Cycle

Birth 120 frys
Lifespan 10 years

Lifespan

In the Wild
3–20 years
In Captivity
5–30 years

Reproduction

Mating System Polygynandry
Social Structure Solitary
Breeding Pattern Transient
Fertilization Substrate Spawning
Birth Type Substrate_spawning

Loricariidae, the armored or suckermouth catfishes (plecos), are diverse. They lay eggs on hard or hidden sites and sperm meets eggs outside the body. Males usually guard and fan the clutch. Adults are solitary; many males mate with several females.

Behavior & Ecology

Social Aggregation Group: 3
Activity Nocturnal, Crepuscular, Cathemeral, Diurnal
Diet Omnivore Periphyton (algae-biofilm) mixed with detritus scraped from hard surfaces

Temperament

Temperament spans from generally peaceful, non-predatory grazers/detritivores to strongly territorial shelter-guarders; aggression is most often intraspecific (especially male-male) and focused on caves/logs/prime surfaces rather than active pursuit.
Many species are cryptic/resting by day and forage at dusk/night; however, some (often in clearer, flowing waters) are regularly active by day, and activity can shift with predation pressure, competition, and food availability.
Feeding ecology is diverse: widespread periphyton/algae scraping and detritivory, frequent wood-gouging/xylophagy in some lineages, and occasional omnivory; social spacing often tracks how defendable the food is (diffuse films vs. discrete wood/caves).
Family-level size diversity is high: adults range from very small species (~3-5 cm standard length) to very large forms (~60-70+ cm), with corresponding shifts in space use and tolerance of conspecifics.
Lifespan varies broadly across the family: commonly ~5-10 years in many small/medium species, with ~10-20+ years reported for larger-bodied taxa (often longer in captivity than in the wild).

Communication

Pectoral-fin spine stridulation producing clicks/creaks/squeaks Often during handling, disputes, or nest defense
Low-frequency drumming or pulses in some taxa Associated with agitation or social interactions
Tactile contact and pushing/locking at shelters; physical jostling during contests
Visual displays: fin erection, lateral posturing, head-down 'bracing,' and presenting armored flanks in close-range interactions
Odontode (dermal tooth) erection and rubbing as close-range signals in some groups, especially during male-male interactions and breeding contexts
Chemical cues likely important for species recognition, reproductive readiness, and locating conspecifics in turbid or dark habitats
Substrate-associated signaling: suction/rasping on surfaces and vibration transmission during grazing or nest attendance Likely incidental but potentially informative at close range

Habitat

Biomes:
Freshwater Wetland Tropical Rainforest Tropical Dry Forest Savanna Temperate Forest Temperate Grassland +1
Terrain:
Riverine Valley Plains Hilly Mountainous Rocky Sandy Muddy +2
Elevation: Up to 11482 ft 11 in

Ecological Role

Benthic grazer-detritivore/omnivore that links primary production (algae/biofilm) and decomposing organic matter to higher trophic levels, with substantial variation among lineages and habitats.

Controls periphyton/biofilm biomass on submerged surfaces (grazing pressure) Recycles nutrients by processing detritus and biofilm and excreting fine particles Bioturbates sediments during feeding, influencing benthic habitat structure Facilitates decomposition and carbon flow in wood-rich systems (in wood-associated feeders) Provides prey/biomass for larger fishes, birds, reptiles, and mammals; contributes to food-web stability

Diet Details

Main Prey:
Aquatic insect larvae Small crustaceans Worms and other benthic invertebrates Small mollusks and snails Fish eggs and small fish Carrion
Other Foods:
Periphyton Algae Detritus Plant detritus Wood and associated biofilm Aquatic plants Fruit and seed material +1

Human Interaction

Domestication Status

Wild

Loricariidae (armored suckermouth catfishes, often called plecos) are not truly domesticated. Most stay genetically like wild fish. Many species are bred in captivity for aquariums, sometimes for color or fin traits. Some are still wild-caught, while common algae plecos such as Hypostomus and Pterygoplichthys are often farmed.

Danger Level

Low
  • Pectoral/dorsal fin spines can puncture skin during handling; wounds can become infected if not cleaned.
  • Some large species can cause painful scrapes or minor injury when thrashing in nets or when handled improperly.
  • Aquarium-related risks: bites are uncommon but possible; more often injuries occur from spines or from lifting heavy tanks/equipment rather than from the fish directly.
  • Ecological/indirect risk: invasive loricariids can damage fisheries, shorelines, and infrastructure (burrowing in banks), creating economic and environmental harm rather than direct human injury.

As a Pet

Suitable as Pet

Legality: Plecos (Loricariidae) are usually legal as pet fish, but rules vary by species and place. Some have export or collection rules; some large Pterygoplichthys/Hypostomus are banned. Releasing them is often illegal and harmful.

Care Level: Experienced

Purchase Cost: $5 - $500
Lifetime Cost: $300 - $15,000

Economic Value

Uses:
Ornamental aquaculture/aquarium trade Capture fisheries (local/regional) Research/education Invasive-species management (cost/negative economic impact)
Products:
  • live aquarium fish (wild-caught and captive-bred)
  • breeding stock and specialty morphs/varieties
  • human food in some regions (small-scale/local markets; varies by species)
  • bycatch/biomass removal products in invaded areas (occasionally used for fishmeal/fertilizer or local consumption; highly variable)

Relationships

Related Species 10

Callichthyid armored catfishes Callichthyidae Shared Order
Thorny catfishes Doradidae Shared Order
Long-whiskered catfishes Pimelodidae Shared Family
Naked suckermouth catfishes Astroblepidae Shared Family
Bristlenose plecos Ancistrus Shared Family
Sailfin plecos Pterygoplichthys Shared Family
Plecos Hypostomus Shared Family
Zebra and tiger plecos Hypancistrus Shared Family
Otocinclus Otocinclus Shared Family
Wood-eating/wood-grazing plecos Panaque Shared Family

Ecological Equivalents 5

Animals that fill a similar ecological role in their ecosystem

Hillstream loach Balitoridae Often occupy fast-flowing, rock-surface habitats and graze biofilm and algae using ventral adaptations for clinging. Ecologically similar to many rheophilic loricariids, though unrelated (they belong to different orders).
Chinese algae eater Gyrinocheilus aymonieri Occupies aquarium and riverine niches as a surface-grazing fish that scrapes algae and biofilm; performs a similar functional role to many small-to-medium plecos despite being from a different lineage.
Siamese algae eater Crossocheilus siamensis Consumes periphyton, algae, and surface biofilm from hard substrates and plants; ecologically overlaps with loricariid catfishes that specialize in grazing attached algae and biofilm.
Nerite snails Neritina spp.; Clithon spp. In streams and aquaria, nerite snails graze hard-surface biofilm and algae similarly to many loricariids; they overlap in microhabitat use (rocks, wood, glass) and diet (biofilm and algae).
Freshwater gobies Gobiidae Some species are benthic, adhere to the substrate in currents, and pick/graze small invertebrates and biofilm, creating a partial niche overlap with stream-dwelling plecos.

Types of Armored Catfish

14

Explore 14 recognized types of armored catfish

Bristlenose pleco Ancistrus cirrhosus
Zebra pleco Hypancistrus zebra
Amazon sailfin catfish Pterygoplichthys pardalis
Common pleco Hypostomus plecostomus
Golden nugget pleco Baryancistrus xanthellus
Royal pleco Panaque nigrolineatus
Clown pleco Panaqolus maccus
Adonis pleco Acanthicus adonis
Leopard frog pleco Peckoltia compta
Whiptail catfish Rineloricaria lanceolata
Royal farlowella (twig catfish) Farlowella acus
Otocinclus (common oto) Otocinclus vittatus
Rubber lip pleco Chaetostoma milesi
Sturisoma whiptail Sturisoma aureum

The Armored Catfish is a seriously invasive species that was originally from South America. Armored Catfish is the common name used to describe the largest family of catfish, Loricariidae. They are known for the bony plates that cover their body. 

These fish look like a typical catfish with whiskers and suckermouths, and are bottom feeders just like you’d guess a catfish to be. Furthermore, they are a popular aquarium fish and are often called “plecos.”

Armored Catfish Classification and Scientific Name

Armored Catfish are the largest family of Catfish (Loricariidae). In this family, there are 92 genera and just over 680 different species. Furthermore, Loricariidae is one of seven families in the superfamily Loricarioidea. 

Some of the fish in the other families also have armor and suckermouths, but not both like Loricariidae. They are commonly called Loricariids, with several genera called “plecostomus” or just “plecos” that are sold in pet stores as aquarium fish. 

The Hypostomus plecostomus was one of the first species imported as an aquarium fish.

suckermouth catfish or common pleco (Hypostomus plecostomus) isolated in a fish tank with blurred background

Suckermouth catfish or common pleco (Hypostomus plecostomus) isolated in a fish tank.

Types of Armored Catfish: The 680 Different Species

As mentioned, there are over 680 species of Armored Catfish in the family Loricariidae. Some of them are:

  • Hypostomus plecostomus:  Commonly referred to as the “pleco,” this is a common fish in the aquarium fish trade. Pet owners have these to clean the aquarium from algae and other contamination. They are also difficult for other fish to harass due to their docile demeanor and thick armor.
  • Hypoptopoma guianense: Small Armored Catfish that live in Guyana in the Essequibo and Nickerie river drainage. It only grows to about 2.5 inches long.
  • Proloricaria prolixa: Armored Catfish endemic to Brazil’s upper Parana River Drainage area. They can grow up to 13.8 inches long.
  • Pterygoplichthys multiradiatus: Commonly known as Orinoco Sailfin Catfish. It has a sail-like dorsal fin and is known for its speckled appearance. It is a popular “pleco” fish for aquariums.

Armored Catfish Appearance 

Armored Catfish appear to be typical catfish from a distance. As you’d expect, they have a large suckermouth that faces downward, allowing them to attach themselves to surfaces through suction. They also have “whiskers” like a cat, called Maxillary Barbels. Unlike a cat, these are sensory organs that help the fish find food.

The bony plates covering their bodies set Armored Catfish apart from normal catfish. Some species may only have the plates in certain areas, mainly on their back, while others have them all over their body. When threatened, these bony plates help to protect the fish from predators.

Since this is the largest catfish family, there are many colors of Armored Catfish with various patterns and body shapes. Some of the smallest are about 1 inch long, with the larger fish growing to 39 inches long.

Typically, they also have a wide body with wide pectoral fins. When threatened, they can lie on the surface of a rock or along the bottom of the body of water and spread their fins out to become difficult for other fish to eat.

Many species have a modified eye called an Omega Iris. A segment of the iris expands downward over the pupil to create a loop that looks like the Greek letter Omega. When light levels are high, this reduces the amount of light transmitted into the eye. It has also been suggested that this offers an amount of camouflage and breaks up the outline of the eye.

The Armored Catfish is a favorite for aquariums, as it is a bottom feeder and helps remove algae.

Armored Catfish Distribution, Population, and Habitat

Where to Find Armored Catfish and How to Catch Them

Originally, Armored Catfish were tropical fish from the freshwater habitats in South America. In the 1950s, they became a popular part of the aquarium trade and subsequently were released into the wild in various parts of the world. 

They are now an invasive species in Florida, Texas, and Mexico. In some Texas rivers, it is believed that they make up 50% of the total fish biomass.

Depending on the size, they can be found in nearly any type of slow stream, pond, lake, or canal. Mostly, they are found along the shoreline and in shallow waters. Catching the smaller fish is typically done with a net; sometimes, the larger ones are caught with a rod and reel using live or artificial bait.

However, the number of fish in the wild is unknown. In non-native areas where they are invasive, it is common for governments to encourage removal from the habitat. There are no limits on catching them, and laws often dictate that they cannot be returned to the water.

Armored Catfish Predators and Prey

Mostly, Armored Catfish eat algae, invertebrates, and any other small organic matter. This makes them well suited to “clean” aquariums, which is why they are popular in the aquarium fish trade. Furthermore, some species are known for their ability to digest wood.

What Do Armored Catfish Eat?

They eat algae, small invertebrates, and other organic waste they find at the bottom of their habitat.

What Eats Armored Catfish?

Predators include other larger fish, birds, river otters, and crocodiles. Humans also catch them, mainly for the aquarium trade and less often for food.

Armored Catfish Reproduction and Lifespan

There are many different species of Armored Catfish, and their breeding habits can vary. However, the most common is burrowing into the shoreline and creating an area to lay their eggs. 

Sometimes, these burrows can be up to three feet deep and destroy the shoreline. 

Females lay several thousand eggs in the burrows twice a year. During the breeding season, males guard the nest until the eggs hatch, which takes about 20 days.

View of suckermouth of armored catfish

The armored catfish uses its suckermouth to ingest algae and small invertebrates for food.

Armored Catfish in Fishing and Cooking

Typically, Armored Catfish are not pursued in recreational sport fishing. Since they feed on algae and small organic matter, it is not as easy to catch them with a rod and reel. 

However, some larger species that eat small invertebrates can be caught with natural bait such as worms or artificial bait such as a “pig and jig.” 

A pig is an artificial lure that looks like a small frog and is heavily scented. This is placed onto a hook of a jig that is simply a hook with a small head painted to resemble a minnow head. Usually, there is also a skirt around the hook made from strips of colored plastic.

Due to the bony plates, Armored Catfish are not easily cleaned for cooking. The body can be split open like a crab, or the meat can be cut away from the skin. The meat is white and flaky. However, it usually does not have much flavor, depending on the water the fish lives in.

Because of the difficulty in catching, the difficulty in cleaning, and the lack of flavor, there is no real market for Armored Catfish as food in the United States. In Brazil, especially in rural areas, they are sold live in markets and commonly eaten grilled or in soups.

You can click here for more information on catching and cleaning these fish.

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Sources

  1. Los Angeles Zoo / Accessed September 16, 2022
  2. Wikipedia / Accessed September 16, 2022
  3. Coastal Angler Magazine / Accessed September 16, 2022
  4. Eat the Invaders / Accessed September 16, 2022
Kristin Hitchcock

About the Author

Kristin Hitchcock

Kristin is a writer at A-Z Animals primarily covering dogs, cats, fish, and other pets. She has been an animal writer for seven years, writing for top publications on everything from chinchilla cancer to the rise of designer dogs. She currently lives in Tennessee with her cat, dogs, and two children. When she isn't writing about pets, she enjoys hiking and crocheting.

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Armored Catfish FAQs (Frequently Asked Questions)

Armored Catfish are native to South America, and can be found in most of the freshwater streams, rivers, and ponds throughout the continent.  They can also be found in Florida, Texas, and Mexico where they are an invasive species.