A morphometric investigation of suckermouth catfish specimens collected from the Upper and Lower Morass of Black River, St. Elizabeth, Jamaica was conducted between June 2007 and May 2008. Descriptions of 39 morphometric and 15 meristic measures are given. Taxonomic assessment through the application of dichotomous keys, photographic identification, and comparison with other morphometric work on similar species, identified the loricariid as Pterygoplichthys pardalis (Pisces, Loricariidae). Further analysis revealed that populations of P. pardalis in the Upper Morass have relatively longer heads, longer snouts, longer and deeper caudal penduncles, and deeper dorsal fins compared with individuals from the Lower Morass. Principal Component Analysis (PCA) showed no distinct groups of P. pardalis occurring throughout the Black River Basin. Both populations exhibited allometric growth and the relationships between length and weight in the P. pardalis populations were significant and linear.