Dorsal spines (total): 17-19; Dorsal soft rays (total): 13-15; Anal spines: 8-10; Anal soft rays: 11-13; Vertebrae: 32-34. Diagnosis: An elongate Paretroplus distinguished from all congeners except P. kieneri by the presence of a blotchy and mottled, orangish-brown to golden-brown, pigmentation pattern, the absence of both vertical bars and a horizontal striping pattern on the flanks, and the presence of a fleshy snout that extends both rostral to the lips and also ventrally to cover a portion of the upper lip (Ref. 78623). Paretroplus gymnopreopercularis is distinguished from P. kieneri by the presence of an asquamate preopercle, vs. fully scaled or scaled except along the ventral margin, and a blunt, strongly convex predorsal profile, vs. pointed; in P. gymnopreopercularis the second lacrimal plate is excluded from the orbit margin owing to contact of the first lacrimal plate and the third infraorbital bone in series, vs. narrow prong of the second lacrimal plate extending into the orbit margin in P. kieneri; in addition, P. kieneri is conspicuously blotchy, mottled, and speckled, and generally exhibits dark gray colouration; in contrast, P. gymnopreopercularis is characterized by a weakly mottled and for the most part uniform chain-link pigmentation pattern, owing to darkly pigmented scale margins, and is never dark gray, but orangish brown to golden brown overall (Ref. 78623).
Description: An elongate, shallow bodied and comparatively small Paretroplus; body laterally compressed; head blunt and snout moderately to strongly convex and rounded, lending the fish a beaked appearance; predorsal profile markedly curved; dorsal body outline moderately curved, ventral outline mostly straight, except posteriorly; caudal peduncle somewhat short, moderately deep, and laterally compressed, yet much longer and shallower than members of the deep-bodied clade; no sexually dimorphic characters readily apparent (Ref. 78623). Total vertebral count 32-34, with formulae of: 14+18, 14+19, 15+18, and 15+19, precaudal and caudal vertebrae, respectively (Ref. 78623). Jaws isognathous; single row of spatulate unicuspid teeth in both upper and lower jaws; teeth laterally expanded, flattened at crown, and procumbently implanted; in upper jaw, tooth on either side of premaxillary symphysis greatly enlarged, other teeth laterally graded in size; lower-jaw teeth at symphysis not enlarged, but somewhat reduced in size compared to adjacent lateral teeth, presumably to accomodate enlarged upper symphyseal teeth; teeth in upper jaw number 4 or 5 on each side, and total 8-10; teeth in lower jaw number four or five on each side, and total nine; upper and lower-jaw teeth generally widely set; symphyseal teeth, and sometimes adjacent lateral teeth, in both upper and lower jaws closely set (Ref. 78623). Upper and lower pharyngeal tooth plates well developed and dentition robust; dentition on lower pharyngeal tooth plates hooked and bicuspid both laterally and anteriorly, becoming progressively enlarged medially; robust molariform teeth present posteromedially; lower pharyngeal jaws well sutured, with numerous interdigitating sutures on posteroventral margin; five or six robust tooth plates cover majority of dorsal surface of fourth ceratobranchial bones; tooth plates occasionally become fused; tooth plates not confluent with outer-row gill rakers of fourth ceratobranchial elements; dentition on fourth ceratobranchial tooth plates unicuspid or weakly hooked and bicuspid laterally, hooked an bicuspid medially; dentition on third upper pharyngobranchial tooth plates becoming robust medially; dentition on third upper pharyngobranchial tooth plates molariform posteromedially, hooked and bicuspid laterally and anteromedially; dentition on second pharyngobranchial tooth plates hooked and bicuspid, and arrayed in three rows (Ref. 78623). Nine or 10 triangular, somewhat elongate gill rakers arrayed along lower limb of first gill arch; some rakers weakly to moderately denticulate dorsomedially; all other lower-limb rakers short and strongly denticulate dorsally, and essentially spherical in shape; teeth on rakers of gill arches 2-4 as long or longer than raker itself; epibranchial rakers on first gill arch elongate, numbering six to eight (Ref. 78623). Body covered with large, regularly imbricate, cycloid scales; well-developed scale ridges present along dorsal- and anal-fin bases; scale ridges free from spiny dorsal and anal fins, but becoming weakly attached to both soft dorsal and anal; pelvic axillary scale present and well developed; lateral-line scales number 37-39; interpelvic scale well developed and elongate; ventral chest scales reduced in size and embedded; those along ventral midline smallest; three rows of scales on cheek; occasionally an incomplete fourth row present; opercle, subopercle, and interopercle scaled; preopercle asquamate; snout and lacrimal asquamate; scales on head extend well anterior of a vertical through anterior margin of orbit; scales on caudal fin reduced in size and extending posteriorly 2/3 to over 3/4 length of fin on dorsal and ventral lobes, and about 1/4 to 1/3 length of fin medially (Ref. 78623). Dorsal with XVII-XIX spines, 13-15 soft rays; anal with VII-X spines, 11-13 soft rays; origin of dorsal fin slightly posterior of vertical through pectoral-fin insertion; caudal fin emarginate, trailing margins of upper and lower lobes weakly produced in larger individuals; pectoral fin broad and rounded at distal margin; distal margins of soft dorsal and anal fins mildly produced and pointed in larger specimens, and extend slightly beyond origin of caudal fin; pelvic fins extend slightly beyond anal-fin origin when adducted (Ref. 78623).
Colouration: Colouration in life: base body colouration mildly blotchy and spotted orangish-brown, to golden-brown or dark olive; scale margins generally dark olive to dark brown; scale centers much lighter orangish brown to pale golden brown; degree of scale margin pigmentation varies considerably over flank, and some scales solid dark golden-brown to dark brown, creating spotted and blotchy chain-link pigmentation pattern characteristic of species; no additional distinctive markings present on head or flanks; no vertical bars present on flanks, even in juvenile specimens; dorsal fin, anal fin, pectoral fins, and pelvic fins orangish brown to golden brown, and similar to body ground colouration; dorsal fin with some black pigment distally; caudal fin golden brown to brown, and rays dark brown to blackish; juveniles to about 75 mm standard length mottled golden brown and appearing camouflaged, owing to large and irregular blotches on flanks, adults become more uniformly pigmented over flank (Ref. 78623). Colouration in preservative: body ground colouration golden, orangish brown, or golden brown, with varying amount of darker brown spotting and blotching on flanks; scale margins generally darker than centers; this pigmentation pattern more pronounced in some areas, or some scales dark overall, creating spotted and blotchy overall appearance; no other distinctive markings; body pigmentation generally uniform and not noticeably darker dorsally; unpaired fins and pectoral fins pale golden brown to light brown; pelvic fins golden brown to grayish brown; juveniles to about 75 mm standard length mottled golden brown and appearing camouflaged, owing to large and irregular blotches on flanks, adults become more speckled and spotted (Ref. 78623).