Morphology Data of Oreochromis niloticus
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 males alike females
Different colors different colors in juveniles and adults
Remarks

Descriptive characteristics of juvenile and adult

Striking features none
Body shape lateral fusiform / normal
Cross section compressed
Dorsal head profile more or less straight
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: teeth in jaws with stout shafts, in 4 or 5 series; outer teeth of young bicuspid becoming tricuspid in adults; number of vertebrae relatively low (30-31); 32-33 scales in lateral line series; modal dorsal fin formula XVI 12; lower pharyngeal bone slender, with its width 29.0-32.4% head length, a little less to a little more its length; toother area of lower pharyngeal bone rather small, its median length contained 1.1-1.5 times in length of the blade; caudal peduncle length 10.0-13.5% standard length and 0.65-0.9 of its depth; pectoral fin 35.0-43.2% standard length; caudal fin with vertical stripes distally, but proximal markings more irregular in adult (Ref. 2).

Description: 7-9 scales between pectoral and pelvic fins (sometimes 6 in young) (Ref. 55985).

Coloration: pelvic and anal fins of breeding males tipped with dark grey, while their throat, chest and belly are dusky grey; females and young with pale slate-grey body and white chest, belly and pelvic fins; black or dark grey lappets and upper edge to dorsal fin; vertical stripes of caudal fin dark brown on a light grey background; pectoral rays red to light brown; flanks may bear 7-8 vertical bars (Ref. 2).

Ease of Identification

Meristic characteristics of Oreochromis niloticus

Lateral Lines 2 Interrupted: No
Scales on lateral line 32 - 33
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line 4 - 5
Scale rows below lateral line
Scales around caudal peduncle 19 - 20
Barbels 0
Gill clefts (sharks/rays only) absent
Gill rakers
on lower limb 20 - 23
on upper limb
total
Vertebrae
preanal
total 30 - 31

Fins

Dorsal fin(s)

Attributes no striking attributes
Fins number 1
Finlets No. Dorsal   0
Ventral  0
Spines total 16 - 17
Soft-rays total 12 - 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 9 - 11

Paired fins

Pectoral Attributes  more or less normal
Spines     
Soft-rays   
Pelvics Attributes  more or less normal
Position    thoracic
Spines     
Soft-rays   
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