This species is distinguished by the following characters: scales on cheeks and opercle; scales in predorsal midline 8-10; unbranched pectoral fin rays 17-18; unbranched 5th pelvic fin ray 40-47% length of 4th ray; total gill rakers 21-22; broad interorbital (56-79% pupil width) with narrow crease-like postorbital groove, ending at posteriormost papilla in row p; papillae in row p 8, with 2 papillae ventral to papilla row n; nasal apparatus small and situated on anterior one-third of snout with posterior nares forming posterodorsal margin of nasal sac; colour when alive or freshly collected has the dorsal surface of eye light blue; preserved specimens with melanophores on dorsal surface of snout and mostly adjacent to nasal capsules (Ref. 118315).

Differs from Trimma blematium by having 17-18 pectoral fin rays (vs. 16), unbranched 5th pelvic fin ray (vs. branched), with 8 papillae in row 'p' (vs. 7 papillae); and in live specimens, the blue colour over the top of the eyes is less darker in this species than in T. blematium (Ref. 118315).