Morphology Data of Oreochromis mossambicus
Identification keys
Abnormalities
Main Ref. Trewavas, E., 1983
Appearance refers to Male; Female
Bones in OsteoBase

Sex attributes

Specialized organs no special organs
Different appearance always different morphology between mature adults
Different colors
Remarks Jaw structure (premaxilla width and length, mouth width, snout length) and height of dorsal and anal fins different in males and females, with males having larger and more robust jaws, and pointed (versus rounded) dorsal and anal fins (Ref. 44586).

Descriptive characteristics of juvenile and adult

Striking features none
Body shape lateral fusiform / normal
Cross section compressed
Dorsal head profile clearly concave
Type of eyes more or less normal
Type of mouth/snout more or less normal
Position of mouth terminal
Type of scales cycloid scales
Diagnosis

Diagnosis: snout long; forehead with relatively large scales, starting with 2 scales between the eyes followed by 9 scales up to the dorsal fin (Ref. 3058, 3060). Adult males develop a pointed, duckbill-like snout (Ref. 52307) due to enlarged jaws, often causing the upper profile to become concave (Ref. 2, 7248, 12524, 13337, 52307), but upper profile convex in smaller specimens (Ref. 1870, 6460). Pharyngeal teeth very fine, the dentigerous area with narrow lobes, the blade in adults longer than dentigerous area; 28-31 vertebrae; 3 anal spines; 14-20 lower gill-rakers; genital papilla of males simple or with a shallow distal notch; caudal fin not densely scaled; female and non-breeding male silvery with 2-5 mid-lateral blotches and some of a more dorsal series; breeding male black with white lower parts of head and red margins to dorsal and caudal fins (Ref. 2).

Description: moderately deep-bodied (Ref. 7248, 52307), but very variable according to food availability (Ref. 5214). Head profile straight in juveniles and females (Ref. 7248). Mouth large (Ref. 1870, 2989, 53262, 52307, 54167). Lower jaw prominent; lips thick (Ref. 3058, 3060). Maxillary ending between nostril and eye in females and immature males (Ref. 2), in breeding males (Ref. 2) mouth reaching to below anterior border of eye (Ref. 1870, 2989, 53262, 54167, 54759) or a little beyond (Ref. 1870, 2989, 53262, 54167). Eye with yellow ring around pupil (Ref. 57960). Otoliths: sulcus with nearly straight crista inferior at the transition between ostium and cauda (thus no ventralward widening of the ostium is present) (Ref. 56279). 2-3 series of scales on cheek (Ref. 2, 552, 1870, 2989, 3058, 3060, 6460, 53262, 54167). Scales cycloid (Ref. 1870, 2989, 3058, 4904, 5728, 53262, 54167). Scales on belly small, breast scales even smaller (Ref. 3058). Large scales on opercle (Ref. 1870, 53262), in 3 rows (Ref. 54759). 17-23 scales in upper part of lateral line, 10-17 in lower part (Ref. 1870, 2989, 3058, 54167). 9-12 predorsal scales (Ref. 57928). 15 precaudal vertebrae; 15-16 caudal vertebrae; 12-13 pairs of pleural ribs; 2 pairs of epineurals; 6 pairs of epipleurals; ventral vertebral apothysis on third vertebra (Ref. 57928). Gill-rakers short (Ref. 1870, 2989, 5214, 6465, 12524, 13337, 54167) and thick (Ref. 54167). Dorsal fin spines subequal from the sixth; dorsal soft rays a little longer than longest spines (Ref. 54167). Last dorsal spine the longest (Ref. 1870, 54167). Soft part of dorsal and anal fin long and pointed (Ref. 1870, 3058, 3060, 4904, 53262), especially in males (Ref. 44586). Dorsal fin with 25-28 pterygiophores (Ref. 57928). Pectoral fin (nearly) as long as head (Ref. 1870, 2989, 53262, 54167), pointed (Ref. 1870, 6460, 53262, 54759), reaching to vent (Ref. 6460, 54167) or to a little beyond origin of anal fin (Ref. 1870, 2989, 53262, 54167, 54759). 4-6 scales between bases of pectoral and pelvic fins (Ref. 2). Anal fin with 11-12 pterygiophores (Ref. 57928). Outer rays of pelvic fins slightly produced, reaching to vent (Ref. 1870, 54167) or beyond origin of anal (Ref. 1870, 2989). Caudal fin scaly in the basal half (Ref. 1870, 6460, 53262), the angles sometimes rounded (Ref. 2, 54167). Central caudal fin skeleton with 3 epurals, 5 hypurals and 2 pairs of uroneurals (Ref. 57928). No genital tassel (Ref. 55077).

Coloration: basic melanin pattern of 2 horizontal and 6-7 vertical bars never fully realized; more commonly, at least in preserved specimens, females and sexually inactive males have no bands, but may have the intersection points of the facultative bands represented by 3-4 upper and 2-5 mid-lateral blotches, or some or all of these may be present (Ref. 2). Basic body coloration silvery grey (Ref. 2, 52307) to greenish grey, sometimes a more bluish colored head (Ref. 52307). Belly greyish (Ref. 4904, 5214, 54167). Spiny part of dorsal fin light with dark mottling (Ref. 3058). Soft dorsal and anal, and caudal and pelvic fins blackish (Ref. 2989, 3058, 3060, 54167). Pectoral fins colorless (Ref. 3058, 3060). Indistinct, dark opercular spot present (Ref. 1870, 2989, 3058, 3060, 53262, 54167, 54759). Vertical fins uniform (Ref. 54167), blackish with more or less distinct whitish spots(Ref. 552) or with large or small, fused or non-fused, dark spots on a pale background (Ref. 6460, 54167), given a darker aspect to these fins (Ref. 6460). 3 black blotches present in juveniles but possibly obscured in adults due to the dark body coloration of breeding males or old adults (Ref. 12524, 13337).

Female and non-breeding male: dirty yellowish-olive (Ref. 12522) or silvery-gray, with 2-5 mid-lateral blotches and some of a more dorsal series (Ref. 2, 52307). Sometimes a series of more or less distinct spots along the side of the body above and below the upper lateral line (Ref. 54167).

Breeding male: uniform dark olive-brown (Ref. 4904, 54167), deep blue-black (Ref. 2) or black, with white lower parts of head (Ref. 2, 4904, 7248, 54167), including throat, lower lips, lower parts of cheeks and opercles, but with a dark blue to black base to the throat (Ref. 12501, 52307), and red margins to dorsal and caudal fins (Ref. 2, 7248, 12522, 12501, 12524, 13337, 52307). Dorsal fin with light coloured spots on membrane between spinous and soft rays (Ref. 12524, 13337). Caudal fin olive-green with light coloured spots on anterior section (Ref. 12524, 13337), but may sometimes appear totally red (Ref. 52307). Tip of dorsal and extremity of caudal lobes yellowish (Ref. 4904, 54167). Anal fin dark gray (Ref. 52307) or olive-green (Ref. 12524, 13337), sometimes with a thin red/orange margin (Ref. 12501, 12522, 12524, 13337, 52307). Unpaired fins normally exhibit greenish to silvery iridescent dots (Ref. 52307). Pectoral fin rays red (Ref. 2). Pectoral and pelvic fins olive-yellow (Ref. 12524).

Juveniles: body silvery (Ref. 2, 5214, 6465, 7248, 12524, 13337, 55020, 57960) or olive-brown, light on belly (Ref. 54167). Scales with dark outer edge (Ref. 54167). Usually 5-8 or more indistinct dark cross bars on body (Ref. 2, 6460, 7248, 39866, 54167, 55020), often in addition to the 2 series of blackish spots (Ref. 54167), but with no horizontal stripes (Ref. 2). Dark opercular spot (Ref. 6460, 54167), on posterior dorsal edge of operculum (Ref. 55020). Black spot at base of anterior rays of soft dorsal (Ref. 552, 54167) and 1-2 whitish spots enclosed by dark streaks (Ref. 54167). Oblique streaks (Ref. 6460) or translucent round spots (Ref. 55020) on soft dorsal. Anal dark at base with a light outer half (Ref. 54167), with oblique streaks (Ref. 6460). Caudal dark at base, light in centre, a black outer ridge (Ref. 54167), with 2-3 bars across the fin (Ref. 6460). Tilapia-spot present (Ref. 2, 5214, 6465, 12501), conspicuous in younger fish persisting albeit faintly to 8cm (Ref. 55020). Fins flesh coloured (Ref. 12524, 13337), all except soft dorsal immaculate (Ref. 55020).

Ease of Identification

Meristic characteristics of Oreochromis mossambicus

Lateral Lines 2 Interrupted: No
Scales on lateral line 27 - 34
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line 3.5 - 5
Scale rows below lateral line 10 - 16
Scales around caudal peduncle 16
Barbels 0
Gill clefts (sharks/rays only) absent
Gill rakers
on lower limb 14 - 22
on upper limb
total
Vertebrae
preanal
total 28 - 31

Fins

Dorsal fin(s)

Attributes extending over most of the back length
Fins number 1
Finlets No. Dorsal   0 - 0
Ventral  0 - 0
Spines total 15 - 18
Soft-rays total 10 - 13
Adipose fin absent

Caudal fin

Attributes more or less truncate; more or less normal

Anal fin(s)

Fins number 1
Spines total 3 - 3
Soft-rays total 7 - 12

Paired fins

Pectoral Attributes  more or less normal
Spines     1
Soft-rays   11 - 15
Pelvics Attributes  more or less normal
Position    thoracic  beneath origin of D1
Spines     1
Soft-rays   5 - 5
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
Entered by Luna, Susan M.
Modified by Musschoot, Tobias
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