Species: Oreochromis aureus, Blue Tilapia

Oreochromis aureus (Steindachner, 1864)

Blue Tilapia

Body an elongate oblong; 1 pair of nostrils; top jaw highly protrusible; teeth fine, close set, in several rows on jaws, 3-5 rows, outer row 2-pointed, outer row readily movable; fine teeth on throat plate that is longer than wide; gill rakers simple, lower rakers 18-26; one dorsal fin XVI (XIV-XVII), without a notch between spines and rays, 13 (12-15); anal fin III, 9-11; scales large, 2-3 horizontal rows on cheek, 4-5 rows between dorsal origin and lateral line; tail fin straight; genital papilla large, elaborate; lateral line in 2 straight overlapping sections, with 30-33 scales.

Female and non-breeding male grey green; a blackish blotch at top corner of opercle; 8-10 indistinct dark bars on body and tail base; dark fish with a dark spot at front of each body scale; tail fin without distinct narrow dark bars, with irregular dark marks or dark reticulum with white/clear interspaces; dorsal and anal fins with irregular rows of pale spots on their bases; juveniles with a dark spot on base of dorsal fin rays. Breeding male: dark grey head, body and fins; intense metallic blue cast to head; iris red; a black blotch at top corner of opercle; edge of dorsal fin dark red, edge of tail fin bright pink, those edges pale orange in breeding female.

Reaches 50.8 cm.

Lives in fresh and brackish water.

Depth range: 0-5 m.

Originally from W-NE Africa; introduced widely throughout our region for aquaculture purposes.