Diagnosis: Hylopanchax multisquamatus is distinguished from its congeners by the presence of more scales along the mid-longitudinal series of scales, 27-30 vs. 19-26, and by the possession of an anterior/posterior flank scale height ration, 140%-150% vs. 170%-220% (Ref. 123864). It is distinguished from H. stictopleuron by the number of scales in transversal row, 6 vs. 5; in addition, H. multisquamatus is distinguished from congeners except Hylopanchax thysi, by the presence of a hyaline urogenital male papilla with small black spots in preserved specimens vs. black, and by the presence of a dark-brown reticulate pattern on the flank of both males and females vs. absence or less-conspicuous pattern; finally, H. multisquamatus is distinguished from H. thysi by the presence of 11-12 pectoral-fin rays vs. 13-14, a male caudal peduncle depth-length ratio between 40-45% vs. 53-59%, a body depth of 20.0-23.7% of standard length vs. 25.2-27.8%, a female predorsal length between 66.0-74.8% of standard length vs. 62.0-64.0%, and a female prepelvic length of 42.1-45.1% of standard length vs. 33.7-38.0% (Ref. 123864).

Description: Dorsal profile straight to slightly convex, slightly concave at nape; ventral profile slightly convex from head to origin of anal fin; body laterally compressed, greatest body depth between pelvic and anal fin (Ref. 123864). Snout rounded, mouth directed upwards; lower jaw longer than upper jaw; on both jaws an outer row of enlarged, slightly curved conical teeth, inner teeth row irregularly arranged with smaller teeth; branchiostegal appendages present in adult males (Ref. 123864). Dorsal, anal and caudal fins truncate; pectoral fin approximately rounded, tip reaching vertical between pelvic-fin base and urogenital papilla; pelvic fin short, tip not reaching anal-fin base; pelvic-fin bases in close proximity (Ref. 123864). Scales cycloid, body completely scaled except ventral head surface; dorsal- and anal-fin base without scales; longitudinal scales 27-30, transversal scales 6, scales around caudal peduncle 9-10 (Ref. 123864). Frontal head squamation G-type; one series of large infra-orbital scales; cephalic lateral line system: elongate and straight supra-orbital neuromast groove, medially delimited by a prominent lobe; anterior portion of supra-orbital sensory canal open in a shallow groove, with three neuromasts, posterior portion open in a shallow groove, with three neuromasts; anterior infra-orbital canal open, with two neuromasts; median portion of infra-orbital region with series of 9-11 minute neuromasts; posterior infra-orbital canal open in a shallow groove, with one neuromast; preopercular canal closed in dorsal and ventral portions, with five pores; mandibular canal represented by two neuromasts; in juveniles, all canals open (Ref. 123864). Second pharyngobranchial with four teeth; third pharyngobranchial wide, with well-developed dentigerous plate containing large conical, slightly curved teeth; fourth pharyngobranchial tooth plate with few small conical teeth; fourth ceratobranchial without or with only one teeth; hypurals completely ankylosed except in one specimen with a median aperture in the anterior region of the compound caudal centrum; total vertebrae 31-32, 12 precaudal and 19-20 caudal; first proximal radial of dorsal fin between neural spine of vertebrae 16 and 17; first proximal radial of anal fin between pleural rib of vertebrae 11; gill rakers on first branchiostegal arch 11-12; branchiostegal rays 5; anterior process of angulo-articular slightly downward directed; lachrymal guitar-shaped, anterior and posterior margins sharply curved (Ref. 123864).

Colouration: Colouration in life of male: side of body semi-transparent, silvery with light bluish-green iridescence; anterior region of flank with three to four rows of scales anteriorly edged with black crescent-shaped markings; head brown grey; snout, lower jaw and head ventral portion light grey; mouth orange; dorsum brownish grey; venter bright blue to green iridescence between just behind branchiostegal appendages and caudal peduncle; anal and dorsal fin hyaline with a marginal orange-red band; caudal fin hyaline to yellowish green, with a dark blotch on proximal portion of rays, with an orange marginal band along all fin margins, but more conspicuous on its dorsal and ventral margins; pectoral and pelvic fins hyaline, with an orange-yellow to red colouration at the distal portion; urogenital papilla hyaline with some small black chromatophores; branchiostegal appendages membrane yellow; iris dorsal region black with a light iridescent blue (Ref. 123864). Live colouration of females: side of body semi-transparent; anterior portion of flank silvery blue; venter whitish between point just behind lower jaw and urogenital papilla; all fins hyaline, with a light-orange colouration in proximal portion of caudal-fin rays (Ref. 123864). Colouration in alcohol: overall colouration of body pale-brownish yellow with sparsely distributed minute chromatophores; anterior region of flank with three or four rows of black crescent-shaped blotches on the anterior edge of scales, forming a reticulate pattern on flank; melanophores on nape and along dorsal midline between nape and caudal-fin base; pale-brown chromatophores along whole mid-body line of flank, more visible between pelvic-fin origin and caudal peduncle; melanophores forming a longitudinal stripe on ventral midline, along anal-fin base; overall colouration of head and jaws brown; brown chromatophores on dorsum of head; iris silver, darker close to pupil; all fins hyaline (Ref. 123864).