Morphology Data of Oreochromis korogwe
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 different colors during breeding season only
Remarks Breeding males with throat and chest black (Ref. 2), and conspicuous broad dark vertical bars on the lower half of the body (Ref. 2, 4967).

Descriptive characteristics of juvenile and adult

Striking features none
Body shape lateral short and / or deep
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: A small bodied tilapia (Ref. 118638). About 50% of individuals have IV anal spines, the modal numbers of vertebrae (29), dorsal rays (27) and gill-rakers (15) are low, and the jaws of breeding males are enlarged (Ref. 2). Females, subadult males and juveniles with a silver/grey flank colour, light ventral colour, and characteristic melanin pattern of 7-9 broken vertical stripes on the dorsal side giving a spotted appearance; males darker, with a series of white spots/bars on the flanks; ripe males have red margins on dorsal and caudal, with a reddish tinge to the pectoral fins; males from southern populations showed a bluish sheen and less contrasting male colouration (Ref. 118638). In breeding males the throat and chest are black and broad dark vertical bars are conspicuous on the lower half of the body (Ref. 2, 4967, 54096).

Description: Lips rather thick; maxillary extending nearly to below eye in some males (Ref. 2). Tooth band wide (Ref. 4967, 55060); teeth in 3-5 series; outer bicuspid, or with minor cusp reduced or absent in breeding or recently spent males, 46-66 in outer row of upper jaw; inner tricuspid (Ref. 2). Gill-rakers on lower part of anterior arch 14-16, rarely 17 (Ref. 2). Lower pharyngeal bone with blade as long as or a little longer than toothed area, which has concave sides and fine teeth (Ref. 2). Vertebrae 29-30 (Ref. 2). Scales on cheek usually in 2 rows, occasionally 3, in lateral series 29-31, between origin of dorsal and lateral line 3.5-4, between bases of pectoral and pelvic fins 4-6; small on chest (Ref. 2). Dorsal fin with XVI-XVIII spines and 9-10 soft rays; anal fin with III-IV spines and 9-11 soft rays; caudal fin truncate; pectoral fins short, not reaching anus; pelvic drawn out into a long filament in mature males (Ref. 2, 55060).

Colouration: In alcohol, females and sexually inactive males have the basic melanin pattern very strongly marked, the horizontal and vertical bands usually represented by intense black blotches, which may be contiguous; a blotch on the top of the caudal peduncle is usually well-marked; the caudal fin may be immaculate or may have part of its area crossed by vertical bars or series of spots (Ref. 2). With indications of about 7 vertical black bars across lower horizontal band (Ref. 55060). Line of 4-5 black spots above dorsal lateral line and black spot on dorsal side of caudal peduncle; tilapia-mark an oval black spot near hind end of dorsal fin (Ref. 55060). In some males, the vertical bars are stronger on the lower half of the flanks and the spaces between them on the abdomen, as well as an uneven and variable area on the operculum, may be whitish silver or aluminium-coloured; the branchiostegal membrane is black in males, pale in females; the genital papilla is white in both sexes and in males is conspicuous against the dark background (Ref. 2). In life, breeding males did not have a marked breeding dress and the corner of the caudal fin is white (Ref. 2).

Ease of Identification

Meristic characteristics of Oreochromis korogwe

Lateral Lines 2 Interrupted: No
Scales on lateral line 29 - 31
Pored lateral line scales
Scales in lateral series
Scale rows above lateral line 3.5 - 4
Scale rows below lateral line
Scales around caudal peduncle
Barbels 0
Gill clefts (sharks/rays only) absent
Gill rakers
on lower limb 14 - 17
on upper limb
total
Vertebrae
preanal
total 29 - 30

Fins

Dorsal fin(s)

Attributes extending over most of the back length
Fins number 1
Finlets No. Dorsal   
Ventral  
Spines total 16 - 18
Soft-rays total 9 - 11
Adipose fin absent

Caudal fin

Attributes more or less truncate; more or less normal

Anal fin(s)

Fins number 1
Spines total 3 - 4
Soft-rays total 9 - 11

Paired fins

Pectoral Attributes  more or less normal
Spines     
Soft-rays   
Pelvics Attributes  rays very elongated
Position    thoracic  behind origin of D1
Spines     
Soft-rays   
Main Ref. (e.g. 9948)
Glossary ( e.g. cephalopods )
Entered by Binohlan, Crispina B.
Modified by Boden, Gert
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