Age, growth and reproduction of the endangered jewelfish Hemichromis bimaculatus (Cichlidae) in the valley of Oued Righ (South-eastern Algeria)
Age, growth and reproduction of 493 jewelfish Hemichromis bimaculatus Gill, 1862 in the valley of Oued Righ (Algeria) were studied from December 2010 to December 2011. The total length and weight of the individuals ranged from 21 to 107 mm and 0.20 to 14.9 g, respectively. Monthly follow-up of the scale marginal growth allowed identifying only one growth stop annulus per year, occurring in April. Back-calculations of total length-at-age permitted to determine that the population was composed of three age classes in both sexes. The adjustment to von Bertalanffy growth model was satisfactory with L∞ = 11.6 cm, K = 0.2, to = -0.5. The fitted total length-total weight relationship was W = 0.026 L2.803. Macroscopic examination of gonads and monthly follow-up of gonadosomatic index indicated that spawning occurred once a year between March and June with a peak activity in April-May. The GSI reached a maximum of 1.12% in males and 7.52% in females. The length at first maturity was 4.5 cm for males and 5.7 cm for females.