[4] Loricariids originate from freshwater habitats of Costa Rica, Panama, and tropical and subtropical South America.

Several genera are sold as "plecos", notably the suckermouth catfish, Hypostomus plecostomus, and are popular as aquarium fish.

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.

[citation needed] 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.

[8] Loricariidae is one of seven families in the superfamily Loricarioidea, along with Amphiliidae, Trichomycteridae, Nematogenyidae, Callichthyidae, Scoloplacidae, and Astroblepidae.

[1] The putative Cenomanian member Afrocascudo, initially described as the earliest loricariid catfish in 2024,[2] might represent a juvenile obaichthyid lepisosteiform, possibly a junior synonym of Obaichthys,[16] though this has been disputed based on the complete ossification of the bones indicating full maturity and the absence of important holostean characters.

[18] The family Loricariidae is vastly distributed over both the east and west sides of the Andes mountains, however, most species are generally restricted to small geographic ranges.

[5] They can be found in torrential mountain rivers, quiet brackish estuaries, black acidic waters, and even in subterranean habitats.

The modified mouth and lips allow the fish to feed, breathe, and attach to the substrate through suction.

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[vague].

To achieve suction, the fish presses its lips against the substrate and expands its oral cavity, causing negative pressure.

[23] Also, unlike most other catfishes, the premaxillae are highly mobile, and the lower jaws have evolved towards a medial position, with the teeth pointed rostroventrally; these are important evolutionary innovations.

[22] In most Ancistrini species, sharp evertible cheek spines (elongated odontodes) are often more developed in males and are used in intraspecific displays and combat.

[28] Studies conducted with representatives of some genera of Hypostominae showed, within this group, the diploid number ranges from 2n = 52 to 2n = 80.

However, the supposed wide karyotypic diversity the family Loricariidae or the subfamily Hypostominae would present is almost exclusively restricted to the genus Hypostomus, and the species from the other genera had a conserved diploid number.

[24] Loricariids exhibit a wide range of reproductive strategies, including cavity spawning, attachment of eggs on the underside of rocks, and egg-carrying.

[5] Three species known from subterranean habitats are true troglobites with reduced pigmentation (appearing overall whitish) and eyes: Ancistrus cryptophthalmus, A. galani and A.

[30][31][32] Similar adaptions with reduced pigmentation are known from two loricariids found in deep water in large Amazonian rivers, Peckoltia pankimpuju and Panaque bathyphilus.

[34] A great many species of loricariids are also sold for their ornamental qualities, representing many body shapes and colors.

Most species of loricariids are nocturnal and will shy away from bright light, appreciating some sort of cover to hide under throughout the day.