Chrysichthys

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Chrysichthys
Chrysichthys auratus (above) and Chrysichthys rueppelli, drawing from The fishes of the Nile by George Albert Boulenger.

Chrysichthys auratus (above) and Chrysichthys rueppelli , drawing from The fishes of the Nile by George Albert Boulenger .

Systematics
Overcohort : Clupeocephala
Cohort : Otomorpha
Sub-cohort : Ostariophysi
Order : Catfish (Siluriformes)
Family : Claroteidae
Genre : Chrysichthys
Scientific name
Chrysichthys
Bleeker , 1809

Chrysichthys is a genus of African catfish from the Claroteidae family. The fish are found in West and Central Africa, in the Nile , in the Congo Basin , Lake Tanganyika and in Mozambique .

features

Chrysichthys species are 8 cm to 1.5 m long. You have four pairs of barbels . The head is four to six times longer than it is high. The eyes are large and are on the sides of the head.

Their in most cases relatively high dorsal fin is supported by six, less often five or seven soft rays, which protrude a very short fin spine, followed by a strong, well developed fin spine. The second, large fin spine is slightly serrated at the rear edge. The adipose fin is small to medium in size and never ossified, its base is shorter than the length of the head. The pectoral fins have a serrated fin spine and eight to eleven branched fin rays. The ventral fins located in the middle of the body have a fin spine and five fin rays. The medium-sized anal fin has three to four hard rays and 6 to 12 soft rays. The caudal fin is deeply forked.

Dimorphism

In the Chrysichthys species there is a striking dimorphism between sexually mature and not yet sexually mature males. In sexually mature males, the head becomes wider and the skin and the mucous layer that protects it thicker. The spines of the pectoral and dorsal fin become stronger and less needle-like. In many cases the nasal barbels become longer and the teeth of the palatine bone develop more strongly. This dimorphism occurs particularly strongly in the subgenus Chrysichthys and Melanodactylus , where the jaw teeth are also stronger.

The dimorphism is so pronounced that sexually mature males have been described as separate species, e.g. B. those of C. nigrodigitatus as C. furcatus or males of C. auratus as C. persimilis and C. rueppelli .

species

literature

  • Melanie Stiassny, Guy Teugels & Carl D. Hopkins: The Fresh and Brackish Water Fishes of Lower Guinea, West-Central Africa. Volume 1. ISBN 9789074752206

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