Diagnosis: The presence of ocelli throughout the anal fin of breeding males distinguishes Serranochromis alvum from S. robustus and S. jallae in which the ocelli in breeding males are restricted to the posterior 4-5 membranes of the anal fin (Ref. 123822). The exposed teeth of S. alvum differs from those of S. stappersi and S. altus, which possess small teeth that are buried in the lips; Serranochromis alvum has an emarginate caudal fin, while S. macrocephalus, S. janus, and S. angusticeps have rounded caudal fins; the shorter jaw of S. alvum, 43.4-53.5% of head length, separates it from S. spei, 53.5-57.2% of head length; Serranochromis alvum has 34-36 lateral-line scales, while S. thumbergi possesses more than 39 lateral-line scales; the acute angle of the cleft of the mouth, 50-60° of horizontal, of S. meridianus delimits it from the 30° angle of S. alvum; the long dark pectoral fins which reach past the middle of the dorsal fin separates S. longimanus from S. alvum; the interorbital width, 14.3-15.9% of head length, of S. alvum is narrower than that of S. swartzi, 17.6-19.8% of head length, S. cuanza, 16.3-18.0% of head length, and S. cacuchi, 20.0-21.7% of head length (Ref. 123822).

Description: Body slender, fusiform, and compressed, deepest at origin of dorsal fin (Ref. 123822). Dorsal-fin origin at vertical through posterior edge of operculum, dorsal-fin spines to maximum length over 5-6 spines, spine lappets prominent; soft dorsal rounded behind, extending to base of caudal fin; caudal fin broad, relatively short, little more than half the head length, rectangular and truncate; anal-fin origin closer to caudal-fin base than tip of snout, below vertical through first dorsal soft-ray; soft-rayed section with bluntly rounded hind edge, extending to caudal-fin base; pectoral fin close behind gill slit, ventral on flanks, base sub-vertical, short, not extending beyond pelvic fins, postero-ventral margin bluntly rounded; pelvic fins ventral, origin narrowly behind base of pectoral fin, short, not reaching origin to the anal fin, strong leading spine 2/3 length of fin (Ref. 123822). Caudal peduncle short, 13-18% of standard length, 7.5 times in standard length, slightly longer than deep, ration caudal peduncle length and Caudal peduncle depth 1.1-1.2 (Ref. 123822). Scales small, in 15 even rows across flanks from dorsal-fin origin to anal-fin origin, 16 rows of scales around caudal peduncle, 34-36 in lateral line; upper lateral line gently curved, lower lateral line straight through mid-caudal peduncle; five scale rows between anterior dorsal and lateral line, two scale rows between soft dorsal and posterior end of upper lateral line; nape and chest scales reduced; cheek scales 7-10 (Ref. 123822). Head elongate, 2.5-2.7 times in standard length, 37-39% of standard length, length greater than body depth, pointed with straight predorsal profile extending 20° above horizontal; eyes large, horizontal eye diameter 21.0-26.7% of head length, vertical eye diameter 21.2-25.7% of head length, dorso-lateral in anterior half of head, entirely above level of the mouth and before the dorsal edge of the operculum; interorbit narrow, less than half orbit diameter; snout relatively long, greater than orbit diameter, nares in mid-snout before orbits; lachrymal depth equal to orbit diameter; cheek below and behind orbits deep with 7-10 rows of scales; post orbit half-length of head, interorbit 14.3-5.9% of head length; mouth terminal, large, protrusible, angle of closed jaw of holotype 30° below horizontal, posterior premaxilla to below anterior orbit, lips well developed, even (Ref. 123822). Teeth caniniform, exposed, widely spaced in 2 series on upper and lower jaws (Ref. 123822). First branchial arch with 3-4,1,9-11 gill-rakers; gill-slit large, extending from upper flank opposite dorsal orbit rim in smooth arch to mid-ventral below orbits (Ref. 123822).

Colouration: Preserved specimens yellowish-brown with darker greyish brown interorbital and body bars, ventral surfaces yellow-brown; fins light yellowish with grey markings; head with broad greyish band across lachrymal through eye to upper operculum and opercular spot; body with two lateral black pigment bands and six broad dark brown bars to caudal-fin base reaching from dorsal fin to lower flanks, dark brown spots at base of scales (Ref. 123822). Live males with broad black bar from lachrymal through lower eye across post-orbit to large opercular spot; iridescent pale blue and white patches on cheeks and above post-orbital bar, white lower cheeks and gular, opercle dusted with grey and black below dorsal black bar, pale blue opercular membrane; body bluish-black above, prominent black bars on body with white infused with blue interspaces between bars, below pectoral fins, and on lower flanks and ventral side; dorsal fin with grey-black blotched membranes between anterior spines; dark grey to black blotches with light blocks on membranes between posterior 5-6 spines; soft dorsal with dark grey-black blotches and clear spots on membranes, edges grey; caudal fin with elongate dark grey-black rectangles and white spots on membranes, a lighter creamish brown submarginal band and greyish black marginal band; anal fin with 3-4 rows of deep greyish-red spots between pale yellow bands; pectoral fins with grey rays and translucent hyaline membranes; pelvic fins with clear rays and a sooty dust over rays (Ref. 123822).