Rubber Lip Pleco

The Rubber Lip Pleco (Chaetostoma milesi) is an armored catfish in the family Loricariidae, native to fast-flowing rivers and streams in South America, particularly in Colombia and Venezuela. The common name refers to its thick, fleshy lips, which form a specialized sucker mouth used to grip rock surfaces in strong current while grazing algae. Like other members of the genus Chaetostoma, it is well adapted to oxygen-rich, fast-moving water rather than the sluggish rivers preferred by many other loricariids. The species is a popular algae-control fish in the aquarium hobby due to its efficient grazing habits and manageable adult size.

Rubber Lip Plecos are identified by their armored, flattened bodies and characteristic thick lips.

• Body: robust, dorsoventrally flattened, covered in overlapping bony plates
• Color: mottled grey-brown to olive with darker speckling or blotching for camouflage
• Mouth: broad, ventral, with notably thick, fleshy, rubbery lips forming a strong sucking disc
• Fins: spiny leading rays on the pectoral and dorsal fins, rounded caudal fin
• Size: typically 12-15 cm The unusually thick, soft lips distinguish it from other similarly shaped armored catfish, which tend to have thinner, more rigid oral discs.

Rubber Lip Plecos inhabit fast-flowing rivers and mountain streams in Colombia and Venezuela, favoring rocky substrates with strong current and high dissolved oxygen. They cling to rocks using their fleshy sucker mouths, grazing algae and biofilm from surfaces exposed to flowing water. Water in their native range tends to be cooler and more oxygenated than typical lowland tropical rivers, reflecting their adaptation to upland stream conditions. They are less commonly found in still or slow-moving water, relying on current to maintain algae growth and oxygen levels suited to their physiology.

Rubber Lip Plecos spend most of their time attached to rocks and other hard surfaces, using their fleshy sucker mouths to graze algae and biofilm in areas of strong current. They are generally solitary or loosely tolerant of conspecifics, showing territorial behavior mainly around favored feeding rocks rather than forming true schools. Feeding activity often increases at dusk and during the night, though they can be seen grazing during the day as well. As with other loricariid catfish, males are believed to guard eggs laid in sheltered crevices, though detailed wild reproductive behavior is not extensively documented.