Loricariidae is the largest family of catfish (order Siluriformes), with over 90 genera and just over 680 species. Loricariids originate from freshwater habitats of Costa Rica, Panama, and tropical and subtropical South America. These fish are noted for the bony plates covering their bodies and their suckermouths. Several genera are sold as "plecos", notably the suckermouth catfish, Hypostomus plecostomus, and are popular as aquarium fish.
Common names Members of the family Loricariidae are commonly referred to as loricariids, suckermouth catfishes, armoured catfish, or suckermouth armoured catfish. The name "plecostomus", and its shortened forms "pleco" and "plec", are used for many Loricariidae, since Plecostomus plecostomus (now called Hypostomus plecostomus) was one of the first loricariid species imported for the fish-keeping hobby.
Some loricariids are not normally considered "plecostomus", such as Farlowella catfish.
In their native range, these fish are known as cascudos or acarís.
L-numbers
Some types of loricariids are often referred to by their 'L-number'; this has become common since imports of loricariid catfish from South America often included specimens that had not been taxonomically described. Currently, L-numbers are used not only by fish-keeping enthusiasts, but also by biologists, since they represent a useful stopgap until a new species of fish is given a full taxonomic name. In some cases, two different L-numbered catfish have turned out to be different populations of the same species, while in other cases, multiple (but superficially similar) species have all been traded under a single L-number.
Taxonomy and evolution Because of their highly specialized morphology, loricariids have been recognized as a monophyletic assemblage in even the earliest classifications of the Siluriformes, meaning they consist of a natural grouping with a common ancestor and all of its descendants. Loricariidae is one of seven families in the superfamily Loricarioidea, along with Amphiliidae, Trichomycteridae, Nematogenyidae, Callichthyidae, Scoloplacidae, and Astroblepidae. Some of these families also exhibit suckermouths or armor, although never in the same individual, as in loricariids.
This is the largest catfish family, including about 684 species in around 92 genera, with new species being described each year. However, this family is in flux, and revisions are likely. For example, the subfamily Ancistrinae is accepted as late as the 2006 edition of Nelson's Fishes of the World; it later becomes grouped as a tribe, because of its recognition as a sister group to the Pterygoplichthyini. Under Ambruster, six subfamilies are recognized: Delturinae, Hypoptopomatinae, Hypostominae, Lithogeneinae, Loricariinae, and Neoplecostominae.
Monophyly for the family is strongly supported, except, possibly, the inclusion of Lithogenes. Lithogenes is the only genus within the subfamily Lithogeneinae. This genus and subfamily, the most basal group in Loricariidae, is the sister group to the rest of the family. Neoplecostominae are the most basal group among the loricariids with the exception of Lithogeneinae. However, the genera of Neoplecostominae do not appear to form a monophyletic assemblage. The two subfamilies Loricariinae and Hypoptopomatinae appear to be generally regarded as monophyletic. However, the monophyly and composition of the other subfamilies are currently being examined and will likely be altered substantially in the future. The Hypostominae are the largest subfamily of Loricariidae. It is made up of five tribes. Four of the five tribes, Corymbophanini, Hypostomini, Pterygoplichthyini, and Rhinelepini, include about 24 genera. The fifth and largest tribe, Ancistrini (formerly recognized as its own subfamily), includes 30 genera.
Loricariid fossils are extremely rare. The earliest known definitive taxon is Taubateia from the Late Oligocene-Early Miocene in Brazil. The putative Cenomanian member Afrocascudo, initially described as the earliest loricariid catfish in 2024, might represent a juvenile obaichthyid lepisosteiform, possibly a junior synonym of Obaichthys, though this has been disputed based on the complete ossification of the bones indicating full maturity and the absence of important holostean characters. Within the superfamily Loricarioidea, the Loricariidae are the most derived; in this superfamily, the trend is toward increasingly complex jaw morphology, which may have allowed for the great diversification of the Loricariidae, which have the most advanced jaws.
Subfamilies and genera Loricariidae is divided into the following subfamilies and genera:
Subfamily Lithogeninae Gosline, 1947 (climbing armored catfishes) Lithogenes C. H. Eigenmann, 1909 Subfamily Delturinae Reis, E. H. L. Pereira & Armbruster, 2006 (primitive suckermouth catfishes) Delturus C. H. Eigenmann & R. S. Eigenmann 1889 Hemipsilichthys C. H. Eigenmann & R. S. Eigenmann, 1889 Subfamily Rhinelepinae Armbruster, 2004 (rhinelepine plecos) Pogonopoma Regan, 1904 Pseudorinelepis Bleeker, 1862 Rhinelepis Agassiz, 1829 Subfamily Loricariinae Rafinesque, 1815 (mailed catfishes) Brochiloricaria Isbrücker & Nijssen, 1979 Cheilonimata Provenzano, 2023 Crossoloricaria Isbrücker, 1979 Cteniloricaria Isbrücker & Nijssen, 1979 Dasyloricaria Isbrücker & Nijssen, 1979 Dentectus Martín Salazar, Isbrücker & Nijssen 1982 Farlowella C. H. Eigenmann & R. S. Eigenmann, 1889 Fonchiiloricaria Rodriguez, Ortega & Covain, 2011 Furcodontichthys Rapp Py-Daniel, 1981 Harttia Steindachner, 1877 Harttiella Boeseman, 1971 Hemiodontichthys Bleeker, 1862 Lamontichthys P. Miranda Ribeiro, 1939 Limatulichthys Isbrücker & Nijssen, 1979 Loricaria Linnaeus, 1758 Loricariichthys Bleeker, 1862 Metaloricaria Isbrücker, 1975 Paraloricaria Isbrücker, 1979 Planiloricaria Isbrücker 1971 Proloricaria Isbrücker, 2001 Pseudohemiodon Bleeker, 1862 Pseudoloricaria Bleeker, 1862 Pterosturisoma Isbrücker & Nijssen, 1978 Pyxiloricaria Isbrücker & Nijssen, 1984 Reganella C. H. Eigenmann, 1905 Rhadinoloricaria Isbrücker & Nijssen, 1974 Ricola Isbrücker & Nijssen, 1978 Rineloricaria Bleeker, 1862 Spatuloricaria Schultz, 1944 Sturisoma Swainson, 1838 Sturisomatichthys Isbrücker & Nijssen, 1979 Subfamily Hypoptopomatinae C. H. Eigenmann & R. S. Eigenmann, 1890 (cascudinhos) Acestridium Haseman, 1911 Chauliocheilos Martins, Andrade, Rosa & Langeani, 2014 Corumbataia Britski, 1997 Curculionichthys Roxo, Silva, Ochoa & Oliveira, 2015 Epactionotus Reis & Schaefer, 1998 Eurycheilichthys Reis & Schaefer, 1993 Euryochus E. H. L. Pereira & Reis, 2017 Hirtella E. H. L. Pereira, Zanata, Cetra & Reis, 2014 Hisonotus C. H. Eigenmann & R. S. Eigenmann, 1889 Hypoptopoma Günther, 1868 Isbrueckerichthys Derijst, 1996 Kronichthys A. Miranda Ribeiro, 1908 Lampiella Isbrücker, 2001 Leptotocinclus Delapieve, Lehmann A & Reis, 2018 Microlepidogaster C. H. Eigenmann & R. S. Eigenmann, 1889 Nannoptopoma Schaefer, 1996 Nannoxyropsis Delapieve, Lehmann A & Reis, 2018 Neoplecostomus C. H. Eigenmann & R. S. Eigenmann, 1888 Niobichthys Schaefer & Provenzano, 1998 Otocinclus Cope, 1871 Otothyris Myers, 1927 Otothyropsis Ribeiro, Carvalho & Melo, 2005 Oxyropsis C. H. Eigenmann & R. S. Eigenmann, 1889 Pareiorhaphis A. Miranda Ribeiro, 1918 Pareiorhina Gosline, 1947 Parotocinclus C. H. Eigenmann & R. S. Eigenmann, 1889 Plesioptopoma Reis, Pereira & Lehmann A., 2012 Pseudotocinclus Nichols, 1919 Pseudotothyris Britski & Garavello, 1984 Rhinolekos Martins & Langeani. 2011 Rhinotocinclus Reis & Lehmann A., 2022 Schizolecis Britski & Garavello, 1984 Subfamily Hypostominae Kner, 1853 (suckermouth catfishes) Acanthicus Agassiz, 1829 Ancistomus Isbrücker & Seidel, 2001 Ancistrus Kner, 1854 Andeancistrus Lujan, Meza-Vargas & Barriga Salazar, 2015 Aphanotorulus Isbrücker & Nijssen, 1983 Araichthys Zawadzki, Bifi & Mariotto, 2016 Avalithoxus Lujan, Armbruster & Lovejoy, 2018 Baryancistrus Rapp Py-Daniel, 1989 Chaetostoma Tschudi, 1846 Colossimystax Armbruster & Lujan, 2025 Corymbophanes C. H. Eigenmann, 1909 Cordylancistrus Isbrücker, 1980 Cryptancistrus Fisch-Muller, Mol & Covain, 2018 Dekeyseria Rapp Py-Daniel, 1985 Dolichancistrus Isbrücker, 1980 Exastilithoxus Isbrücker & Nijssen, 1979 Guyanancistrus Isbrücker, 2001 Hemiancistrus Bleeker, 1862 Hopliancistrus Isbrücker & Nijssen, 1989 Hypancistrus Isbrücker & Nijssen, 1991 Hypostomus Lacepède, 1803 Isorineloricaria Isbrücker, 1980 Lasiancistrus Regan, 1904 Leporacanthicus Isbrücker & Nijssen, 1989 Leptoancistrus Meek & Hildebrand, 1916 Lithoxancistrus Isbrücker, Nijssen & Cala, 1988 Lithoxus C. H. Eigenmann, 1910 Megalancistrus Isbrücker, 1980 Neblinichthys Ferraris, Isbrücker & Nijssen, 1986 Panaqolus Isbrücker & Schraml, 2001 Panaque C. H. Eigenmann & R. S. Eigenmann, 1889 Paralithoxus Boeseman, 1982 Parancistrus Bleeker, 1862 Paulasquama Armbruster & Taphorn, 2011 Peckoltia A. Miranda Ribeiro, 1912 Peckoltichthys A. Miranda Ribeiro, 1917 Pseudacanthicus Bleeker, 1862 Pseudancistrus Bleeker, 1862 Pseudolithoxus Isbrücker & Werner, 2001 Pseudoqolus Lujan, Cramer, Covain, Fisch-Muller & López-Fernández, 2017 Pterygoplichthys Gill, 1858 Scobinancistrus Isbrücker & Nijssen, 1989 Spectracanthicus Nijssen & Isbrücker, 1987 Stellantia Armbruster & Lujan, 2025 Transancistrus Lujan, Meza-Vargas & Barriga Salazar, 2015 Yaluwak Lujan & Armbruster, 2019 incertae sedis Microplecostomus Silva, Roxo, Ochoa & Oliveira, 2016 Nannoplecostomus Ribeiro, F. C. T. Lima & E. H. L. Pereira, 2012
Distribution and habitat The family Loricariidae is vastly distributed over both the east and west sides of the Andes Mountains, but most species are generally restricted to small geographic ranges. They are primarily found in freshwater habitats of South America, but several loricariines and hypostomines are native to Panama, and two species (Fonchiiichthys uracanthus and Hemiancistrus aspidolepis) are native to Costa Rica. Species occur in swift-flowing streams from the lowlands up to in elevation. They can also be found in a variety of other freshwater environments. They can be found in torrential mountain rivers, quiet brackish estuaries, black acidic waters, and even in subterranean habitats.
Description and biology This family has extremely variable color patterns and body shapes. Loricariids are characterized by bony plates covering their bodies, similar to the bony plates in callichthyids. (In Latin, lorica means corselet). These fish exhibit a ventral suckermouth, with papillae (small projections) on the lips. When present, the adipose fin usually has a spine at the forward edge. These fish have, when they are present, a unique pair of maxillary barbels. These fish have relatively long intestines due to their usually herbivorous or detrivorous diets. The body is characteristically flattened in this family. Taste buds cover almost the entire surface of the body and fin spines. Body lengths can range from in Nannoplecostomus eleonorae to over in Panaque, Acanthicus, and Pterygoplichthys.
One of the most obvious characteristics of the loricariids is the suckermouth. The modified mouth and lips allow the fish to feed, breathe, and attach to the substrate through suction. The lips were once believed to be unable to function as a sucker while respiration continued, as the inflowing water would cause the system to fail; however, respiration and suction can function simultaneously. Inflowing water passing under the sucker is limited to a thin stream immediately behind each maxillary barbel; the maxillae in loricariids support only small maxillary barbels and are primarily used to mediate the lateral lip tissue in which they are embedded, preventing failure of suction during inspiration. To achieve suction, the fish presses its lips against the substrate and expands its oral cavity, causing negative pressure.