Diagnosis: Eleotris pellegrini is distinguished by second and fourth suborbital free neuromast rows on cheek extending ventrally past horizontal row 'd' ('2,4' pattern), row 'os' not connected with row 'oi' at ventro-posterior margin of operculum ('open' pattern); 15 pectoral fin rays; no teeth on vomer; scales in zigzag series 10-12, and 18-24 in transverse forward series (Ref. 123271). Within the pattern '2.4' group, Eleotris pellegrini differs from E. acanthopoma in having 15 pectoral fin rays vs. 16-17 and 28-34 scales in predorsal series vs. 30-42; it differs from E. vomerodentata by the absence of teeth in the vomer vs. presence; it differs from E. sahanaensis by a greater head length, 31-37% of standard length vs. 30-32%, and more scales in zigzag series, 10-12 vs. 10 (Ref. 123271).

Description: The body is elongated but stocky; the body depth at anus is 17-24% of standard length and the caudal peduncle depth is 10-17% of standard length; predorsal length 42-49% of standard length and preanal length 62-70% of standard length (Ref. 123271). Head 32-37% of standard length, slightly depressed, the snout is pointed; eyes high on head; the mouth is large, as jaw length is 9-14% of standard length, and oblique, the posterior margin of upper jaw reaches the vertical through the half of the eye; upper and lower jaws with multiple rows of small inwardly curved teeth, larger on outer row; a few caniniform teeth in posterior position (Ref. 123271). Dorsal fins mostly VI-I,8-9; first dorsal fin spine separate from and same height as second dorsal fin spine; spines not elongated; anal fin I,8-9 and directly opposite to second dorsal fin; pelvic fins separate, I,5; pectoral fins 15; caudal fin rounded with 15 branched rays (Ref. 123271, 127682). Cycloid scales on top of head, nape, cheek, operculum, pectoral fin base, prepelvic region, and abdomen; ctenoid scales covering flanks; no lateral line canals; 48-56 scales in lateral series, 28-37 in predorsal series, 14-16 in transverse back series, 18-24 in transverse forward series and 10-12 in zigzag series (Ref. 123271). A downward pointing spine at the posterior margin of the preoperculum is covered with skin; gill opening is moderately broad, extending to below the preoperculum; tubular anterior nares overhanging half upper lip, posterior nares open pits (Ref; 123271). Adults with five transverse suborbital free neuromast rows of which second and fourth suborbital free neuromast rows on cheek extend ventrally past horizontal row 'd' ('2.4' pattern); row 'os' not connected with row 'oi' at ventro-posterior margin of operculum ('open' pattern) (Ref. 123271). Urogenital papilla in females rounded, elongated and tapered in males (Ref. 123271).

Colouration: Colour in life of male and female similar: body marbled from light to dark brown, more beige on the back and striped and spotty on the flanks, alternating dark brown and beige; three horizontal dark brown to reddish stripes between eyes and preoperculum and three vertical white ones below the eye; first dorsal fin translucent with two large horizontal dark spotted stripes, one at fin base, one in the middle of the fin; second dorsal and anal fins with 5-6 brownish wavy spotted horizontal stripes; pelvic fins base yellowish; caudal fin brown, with two brown spots anteriorly, several brownish vertical spotted wavy rows; pectoral fins translucent (Ref. 123271). Colour in preservation of male and female similar: body marbled brown, lighter on the back and striped on the flank; three horizontal dark brown stripes between eyes and preoperculum; first dorsal fin with two large horizontal dark stripes, one at fin base, one in the middle of the fin; second dorsal and anal fins with 5-6 brownish wavy spotted horizontal stripes; caudal fin brown, with two brown spots anteriorly, several brownish vertical wavy spotted stripes; pectoral fins greyish (Ref. 123271).