Suckermouth Catfish Identification Guide

Key identification features

• Broad, flattened head with a ventral sucker-disc mouth used for grazing algae off rocks and wood
• Body covered in rows of hard, bony plates rather than true scales
• Brown to gray mottled coloring that provides camouflage against rocks, gravel, and driftwood
• A single stout, serrated spine leading each pectoral fin
• Moderate-height dorsal fin, shorter than that seen in many related armored catfish
• Flattened underside that lets it grip smooth or textured surfaces firmly, even in fast current
• Small eyes with a distinctive iris flap that helps regulate light entering the eye

Common look-alikes

• Sailfin catfish: has a much taller dorsal fin with more rays than the typical suckermouth catfish
• Zebra pleco: shows bold black-and-white banding instead of the mottled camouflage pattern typical of suckermouth catfish

Where you'll see one

Suckermouth catfish are native to freshwater rivers and streams throughout South America, where they cling to rocks, driftwood, and vegetation in flowing water, and they have also been widely introduced elsewhere through the aquarium trade, establishing self-sustaining wild populations in some warm climates around the world.