Pterygoplichthys can be differentiated from most other loricariids due to their large dorsal fins with 9 or more (usually 10) dorsal fin rays, which gives them their common name "sailfin catfish".
These fish have rows of armour plating covering the body; the abdomen is almost completely covered in small plates.
Other characteristics of members of this genus include an underslung suckermouth, evertable cheek plates, adipose fin present, and an enlarged stomach connected to the dorsal abdominal wall by a connective tissue sheet.
P. anisitsi, P. disjunctivus, P. multiradiatus, and P. pardalis lack cheek odontodes, but still possess the evertible cheek plates; this was previously used as a trait to determine these fish as part of the genus Liposarcus.
Species of the P. gibbiceps group (species formerly classified in the genus Glyptoperichthys) are easily recognized by a large crest above the back of their skull.

Color pattern is generally dark brown with either darker spots or lighter spots or vermiculations.
The adult size of a member of Pterygoplichthys can range from about 50–70 cm.

The stomach of Pterygoplichthys is greatly expanded with the posterior portion forming a long, thin sac that is highly vascularized.
Pterygoplichthys can be differentiated from most other loricariids due to their large dorsal fins with 9 or more (usually 10) dorsal fin rays, which gives them their common name "sailfin catfish". These fish have rows of armour plating covering the body; the abdomen is almost completely covered in small plates. Other characteristics of members of this genus include an underslung suckermouth, evertable cheek plates, adipose fin present, and an enlarged stomach connected to the dorsal abdominal wall by a connective tissue sheet. P. anisitsi, P. disjunctivus, P. multiradiatus, and P. pardalis lack cheek odontodes, but still possess the evertible cheek plates; this was previously used as a trait to determine these fish as part of the genus Liposarcus. Species of the P. gibbiceps group (species formerly classified in the genus Glyptoperichthys) are easily recognized by a large crest above the back of their skull.
Color pattern is generally dark brown with either darker spots or lighter spots or vermiculations. The adult size of a member of Pterygoplichthys can range from about 50–70 cm.
The stomach of Pterygoplichthys is greatly expanded with the posterior portion forming a long, thin sac that is highly vascularized.
Pterygoplichthys