Herichthys tepehua is distinguished from H. deppii by having longer head (mean 37% SL, SD 2% SL vs. mean 35% SL, SD 1% SL), shorter distance from the anal fin origin to the hypural base (mean 39% SL, SD 2% SL vs. 42% SL , SD 1% SL), a larger eye (mean 26% HL, SD 3% vs. mean 24% HL, SD 2% HL). It can be diagnosed from H. carpintis in that it has a longer anal fin origin-hypural base distance (mean 39%, SD 2% vs. mean 38%, SD 2%) in SL; deeper cheeks (mean 32%, SD 4% vs. mean 28%, SD 4%) and longer snout (mean 39%, SD 4% vs. mean 37%, SD 3%) all in HL. It also differs from other congeners by the following autapomorphies: 2 conspicuous blue/ green parallel markings on the sides of the cheeks extending from the lip fold to the orbit of the eye. Ground color is blue-green. It shares with H. deppii the absence of iridescent spots/pearls on the body (Ref. 99935).