A small to medium-sized cave-dwelling haplochromine with relatively deep body depth with greatest body depth at base of seventh or eighth dorsal spine (Ref. 82798). Otopharynx antron has a larger eye, 31.4-34.7% of head length, than most other Otopharynx species. It has fewer lateral-line scales (29-31) than Otopharynx argyrosoma and a larger lower-jaw length than Otopharynx heterodon (Ref. 82798). It is distinguished from Otopharynx spelaeotes and Otopharynx lithobates by its primarily unicuspid teeth in the outer rows of the oral jaws, by its smaller horizontal eye diameter, by a deeper caudal peduncle, and additionally from O. spelaeotes by having fewer teeth in the outer row of the left lower jaw (15-19) (Ref. 82798).