Hoplias microlepis is distinguished from all congeners, except species of H. malabaricus group, by the the shape of the dentaries abruptly converging towards the mandibular symphysis (vs. dentaries parallel and only gently converging towards the mandibular symphysis) and by having tooth plates on tongue (vs. absence of tooth plates on tongue). H. microlepis can be separated from H. brasiliensis and H. curupira by having 43-47 scales on lateral line (vs. 38-43 and 34-39, respectively), and from H. australis and H. lacerdae by having 4 pores of the laterosensory system along the ventral surface of dentary (vs. always 5 and 6-8 respectively). It differs from H. aimara by having accessory ectopterygoid and by lacking vertically elongate dark spot on the opercular membrane (vs. absence of accessory ectopterygoid and presence of dark spot). It can be diagnosed from the other members of the H. malabaricus species group by having more circumpeduncular scales (22-24, usually 24 vs. 18-20, usually 20) (Ref. 96873).

Description: Dorsal-fin rays ii, 11-13; anal-fin rays ii-iii, 7-9; pectoral-fin rays i,10-14; pelvic-fin rays i,7; longitudinal series of scales between lateral line and pelvic-fin origin 5.5-6.5 (Ref. 96873).