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Hypostomus plecostomus

Armored Catfishes

Synonym(s): Suckermouth Catfish, Algae Eaters
Class: Actinopterygii
Order: Osteichthyes
Family: Loricariidae

Photographer: United States Geological Survey
Source: United States Geological Survey


The armored catfishes (Family: Loricariidae) are algivorous, mostly nocturnal, with a noticeable sucker located ventrally on the head. Loricariids can range in size from 3 inches to over three feet in adequate conditions. Their flattened ventral surface allows the fish to use their suckers on most substrates. The adipose fin has a spine and pectoral fins have thick, toothed spines that are used in male-male competition and locomotion.

Ecological Threat: With the over-abundance of Loricariids in freshwater ecosystems, local indigenous species can be out-competed and reduced. This could lead to a collapse of freshwater fisheries in addition to the obvious ecological dangers. While the Loricariids were introduced to control algae populations, it is unknown how effective these fish actually are at controlling them.

Biology: Loricariids are cavity builders and can lay more than 300 eggs in their nests. Males guard the nest and the eggs hatch within 4 to 20 days depending on the species. In addition to their successful breeding strategies, Loricariids are hearty fish that can withstand a wide range of ecological conditions. In fact, the fish can gulp air and survive out of water for more than 30 hours.

History: Loricariids otherwise known as plecos are naturally found in tropical South America, Panama, and Costa Rica. However, their range is increasing due to accidental and intentional human introductions throughout the world. Loricariids are frequently released into freshwater bodies in the United States and throughout the world by natural resource managers to remove algae and control aquatic plants. However, their effectiveness in controlling algal and plant growth in natural systems is undocumented. Plecos are also common in the aquarium trade. Perhaps the most ubiquitous species, Hypostomus plecostomus, was found in Texas at the San Antonio River in 2000 and has maintained an obvious presence with a stable population ever since. Hypostomus plecostomus has also been found in Nevada, Hawaii, and isolated specimens from Arizona, Colorado, Connecticut, Louisiana and Pennsylvania have been collected. Hypostomus plecostomus is the most geographically widespread of the Loricariids.

U.S. Habitat: Loricariids can be found in most freshwater habitats in tropical Costa Rica, Panama, and South America, but many species have small natural ranges. They can also be found in some brackish water habitats. Most loricariids are nocturnal. Armored catfish eat algae, invertebrates, and detritus however, there is one genus, Panaque, that is known for eating wood.


Native Origin: Central and South America.

U.S. Present: Florida, Texas, and possibly Wisconsin.

Distribution: Reproducing populations occur in spring-influenced habitats of the San Antonio River (Bexar County), Comal Springs (Comal County), San Marcos River (Hays County), and San Felipe Creek (Val Verde County)




Management stems from controlling the fish trade. Advising owners to avoid releasing Loricariids into local waters is paramount in curbing the invasion.

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Text References

Podkowa, Dagmara, and Lucyna Goniakowska-Witalińska. "Morphology of the air-breathing stomach of the catfish Hypostomus plecostomus." Journal of Morphology. 257.2 (2003): 147–163.

Power, Mary. "Resource Enhancement by Indirect Effects of Grazers: Armored Catfish, Algae, and Sediment." Ecology. 71.3 (1990): 897-904.

Shafland, P. L. "The Continuing Problem of Non-Native Fishes in Florida." Fisheries. 1.6 (1976): 25

Online References:

Dan Foley, PhD. - Sul Ross State University - Rio Grande College -
Krista Capps -

Data Source

Last Updated: 2011-09-07 by Amber Bartelt - Sam Houston State University