Biologie de la reproduction de deux espèces de Chrysichthys (Siliuriforme, Bagridae) du Lac Nokoué et de la lagune de Porto-Novo au Bénin.

The reproductive biology of two Chrysichthys species of lake Nokoue and Porto-Novo lagoon in Benin was studied in 1990-1991. N=1974 C. nigrodigitatus and n =733 C. auratus were caught by artisanal netting. The spawning of the two species occurred from May to November with a maximum intensity during the spate season (August-September-October). The influence of the environmental factors on the maturation of the gonads is discussed. Sexual maturity was attained at a median size of 30,3 cm TL (males ) and 29,3 cm TL (females) in C. nigrodigitatus and of 12,5 cm TL (males ) and 11,9 cm TL (females)i in C. auratus.The diameter of the eggs (stage III) varied from 2,6 to 3,4 mm in C. nigrodigitatus and from 1,2 to 2,8 mm in C. auratus. Absolute fecundity ranged from 4695 eggs (30 cm TL fish) to 7596 eggs (32,cm TL fish) in C. nigrodigitatus (n = 4) and from 89 eggs (8,9 cm TL fish) to 2550 eggs (21,8 TL fish) in C. auratus.(n=42). Fishes spawned in cryptic habitats and the control of eggs seemed to be done by the two partners