Sailfin Catfish Identification Guide

Key identification features

• Heavily armored body covered in rows of bony plates (scutes) rather than true scales
• Flattened, disc-shaped sucker mouth on the underside of the head, used for grazing algae off hard surfaces
• Tall, sail-like dorsal fin with 10 or more rays, which gives the fish its common name
• Dark brown to olive body marked with darker blotches, spots, or a mottled camouflage pattern
• Small eyes set high on a broad head, and a stiff, heavily armored tail base
• Can grow quite large, often reaching 12-20 inches or more in the wild

Common look-alikes

• Common pleco (Hypostomus plecostomus): has a noticeably shorter dorsal fin with only about 7 rays instead of the sailfin's 10 or more, and a less blotchy pattern
• Other Pterygoplichthys species: nearly identical in overall shape and color; reliable field separation usually requires counting dorsal fin rays and comparing head width

Where you'll see one

Sailfin catfish are native to river basins in South America but are now firmly established as an invasive species in warm freshwater canals, lakes, and rivers throughout Florida, Texas, and other subtropical regions worldwide, where they are often seen clinging to submerged rocks, pilings, and concrete walls.