Armored Catfish

Quick Take

• The same fish sold in pet stores to clean aquariums has taken over some U.S. rivers in a way that's hard to believe. That is, until you see the numbers. See their invasive spread →
• Armored Catfish have a bizarre eye feature that no other common fish eye has, and it serves two completely different purposes. Explore the Omega Iris →
• Their nesting behavior is quietly destroying riverbanks in ways most people never connect back to this fish. See their burrowing behavior →
• Some species in this family can digest something most fish simply cannot, and that ability changes how you think about what 'bottom feeder' really means. See what they actually eat →

The Armored Catfish is a highly invasive species 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. They are also a popular aquarium fish, often called “plecos.”

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 fish in the other families have armor or suckermouths, but not both, unlike 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.

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 of algae and other buildup. They are also difficult for other fish to harass due to their docile demeanor and thick armor.
• Hypoptopoma guianense: Small Armored Catfish found in the Essequibo and Demerara-Berbice river drainages in Guyana, as well as the Nickerie River drainage in Suriname. It only grows to about 2.4 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.

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 its body set the Armored Catfish apart from normal catfish. Some species may only have the plates in certain areas, mainly on their backs, while others have them all over their bodies. 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 flat on a rock surface 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 some camouflage by breaking up the outline of the eye.

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, they are believed to 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, governments commonly encourage their removal from the habitat. There are no limits on catching them, and laws often dictate that they cannot be returned to the water.

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. Notably, some species are also 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.

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 a nesting chamber for their eggs. Sometimes, these burrows can be up to three feet deep and destroy the shoreline. 

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

Fishing and Cooking

Armored Catfish are not typically targeted 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 a heavily scented artificial lure that resembles a small frog, placed onto the hook of a jig—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 their bony plates, Armored Catfish are not easy to clean 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 quality of the water the fish lives in.

Because of the difficulty in catching and cleaning them, and their 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.