Diagnosis: A large bodied tilapia, with a slender body and small head and mouth; body depth 2.5-2.8 times in standard length (Ref. 4967, 118638). It can be distinguished by following characters: teeth of jaws with slender shafts in young, uniformly slender in adults; pharyngeal teeth very fine and crowded; dentigerous area with rounded lobes and short apex, its median length nearly always less than that of the blade; pectoral fin 34.3-41.2% of standard length, reaching base of anal fin; anal spines III-V (Ref. 2, 55060). Males and females are characterised by rows of blotched scales across the flanks; males have a pale blue head with dark spots, dark fins with pale spots, and orange margins to the dorsal and caudal; females and non-territorial males plainer and typically paler, and in some populations there is a more olive/yellow gular and ventral region (Ref. 118638). Caudal fin long with very definite vertical black or dark brown stripes (Ref. 55060).

Description: The upper profile of the head is steep and approximately straight (Ref. 2). The mouth is small and the jaws are not enlarged in most fishes; the teeth of the jaws are in 5-7 series in adults, very slender, up to half the posterior outer of the upper jaw becoming unicuspid in bigger fishes, inner tricuspid except the inmost row in a specimen of 203 mm standard length, which includes several unicuspids (Ref. 2). Two rows of scales on the cheek; number of scales in the lateral line series 33-36; scales on chest very small; on the belly the median row and three on each side of it noticeably smaller than the flank scales (Ref. 2). Dorsal fin with XVII-XIX spines and 11-13 soft rays; anal fin with III-IV spines and 10-12 soft rays (Ref. 2). Vertebrae 32-33 (Ref. 2). No genital tassel (Ref. 55060).

Colouration: Non-breeding fishes light grey or grey-green with numerous dark brown or black spots, each on one scale, but of irregular sizes and shapes, and some scales unmarked; seven to nine vertical bars on the body and a mid-lateral longitudinal band generally formed by emphasis of the spots; scales of belly pale with dark edges; spots extending on top and sides of head to varying degrees, often strong at the temporal lateral line pores; dorsal fin with dark spots or reticulum on the spinous part, oblique bars on the soft; anal barred posteriorly; caudal with vertical dark bars proximally, sometimes becoming irregular or fading out distally (Ref. 2, 55060). Mature male with green and purple sheen on the body, cheeks and opercula; dorsal margin bright orange, caudal margin crimson; pelvics and often also edge of anal bluish green; yellow spots on the dorsal and anal fin, and caudal fin yellow to orange; the dark mottlings on the flanks become more intense during aggressive or courting behaviour (Ref. 2). In life the dark spots are accompanied by golden-yellow spots (Ref. 2). The young have 9-14 dark vertical bars on the body, stretching from dorsal to ventral surface, caudal and hind end of anal striped as in adults (Ref. 2, 55060). A well marked black Tilapia-mark on a clear background extending from last dorsal spine to the third or fourth soft ray, and followed by 3 definite black bars on hind end of dorsal fin (Ref. 55060).