Nile tilapia

Oreochromis niloticus

Oreochromis niloticus is a species of fish family of cichlids ( Cichlidae ), which is very widespread with eight subtypes in West, North and East Africa, and also occurs in the Middle East.

Features

Oreochromis niloticus may be about 60 cm long and 4 kg. He has a very high-backed and laterally flattened body covered with cycloid scales. The body height is 40 to 47% of standard length, head length from 31.5 to 40.5 % of standard length, and the lower jaw length 29 to 37 % of head length. The jaws of smaller fish are staffed with 3-4 rows of teeth, larger specimens ( longer than 20 cm ) have 4-6 rows of teeth. The teeth of the outer row of teeth are bicuspid. The lower Pharyngealia is as broad as long or slightly wider. Your ventral keel is longer than the triangular, studded with teeth area. On the lower branch of the first gill arch are 18 to 28 gill Reuse rays.

  • Fins formula: Dorsal XV-XVIII/11-13, Anal III/9-11.
  • Dandruff formula: SL 31-34, 2-3 rows of scales on the sides of the head.
  • Eddy: 30-32.

The most prominent characteristic of Oreochromis niloticus are the vertical stripes on the tail fin. Otherwise, the fish are gray in color and 6 to 9 show vertical, olive stripes on the sides of the body. The belly is whitish, the upper lip green or white, the lower lip white. Dorsal and anal fins are greyish, sometimes with a narrow reddish margin. The pectoral fins are transparent, the pelvic fins gray. During the mating season the males show a reddish tinge on the head, body, back and tail fin.

Way of life

Oreochromis niloticus is found in many freshwater habitats and has a high temperature tolerance ( from 13.5 to 33 ° C). This can be rivers, lakes or irrigation channels. It feeds mainly on phytoplankton and algae. Like all Oreochromis species Oreochromis niloticus is also pD a mouth brooders, where the breeding business is exercised only by the female.

Subspecies

  • Oreochromis niloticus baringoensis Trewavas, 1983; Lake Baringo (Kenya ).
  • Oreochromis niloticus cancellatus ( Nichols, 1923); Lake of the Ethiopian Rift Valley, Basaka Lake and Awash system, but not in Lake Tana and Lake Turkana.
  • Oreochromis niloticus eduardianus ( Boulenger, 1912); Albertnil, Albert, Edward, George, Lake Kivu, Lake Tanganyika and Ruzizi. ( Introduced in Lake Victoria and Lake Kyoga, and in many small lakes and reservoirs in Uganda and Rwanda).
  • Oreochromis niloticus filoa Trewavas, 1983; Awash system without Basaka Lake; possibly also in Akakisee.
  • Oreochromis niloticus niloticus (Linnaeus, 1758); Israel, basin of the Nile from Albertnil to the delta, West Africa (Senegal, Gambia, Volta, Niger and Benue ) and in Chad. In many countries, the subspecies was introduced as a food fish.
  • Oreochromis niloticus sugutae Trewavas, 1983; Northwest Kenya, also in thermal springs.
  • Oreochromis niloticus tana Seyoum & Kornfield, 1992; Lake Tana ( the highlands of Ethiopia).
  • Oreochromis niloticus vulcani ( Trewavas, 1933); Lake Turkana (Kenya) and tributaries, with the exception of the Omo.
Genus Near East Pharyngeal jaw Fish fin Ethelwynn Trewavas Lake Basaka Awash River Lake Albert (Africa) Senegal River Gambia River Omo River FishBase
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