Diagnosis: Paretroplus polyactis is distinguished from congeners by a unique chainlink, or diamond mesh, pigmentation pattern, owing to contrasting dark scale margins and light centers over the entire flank and portions of the head; it is also the only member of the genus in which the entire series of lateral bars is both strongly pigmented and spotted, due to more darkly pigmented scale margins than centers, regardless of size (Ref. 78623). In life, P. polyactis is unique among deep-bodied members of the genus in possessing a bright red iris, a feature shared only with the elongate P. lamenabe (Ref. 78623).