Reproductive Biology and Life History Patterns of the Claroteid, Chrysichthys nigrodigitatus (Lacépède: 1803) from a Man-made Lake in Southern Benin

Abstract

Background and Objective: The success of aquaculture and fisheries management of introduced key species requires knowledge on spawning biology. This study aimed to document the reproductive biological traits of Chrysichthys nigrodigitatus f r om a s and- dr agged artificial lake. Methodology: During 15 months, about 1020 individuals were sampled and examined for its spawning characteristics. Sex ratio, gonadosomatic index (GSI), lengths at first sexual maturity (L 50 ) and batch fecundity (F ) were computed and one-way ANOVA was performed using SPSS computer software. Results: Chrysichthys nigrodigitatus was a prominent species in Lake Ahozon and numerically b made about 11.22% of the fish assemblages. The population was dominated by females (67.84%) and showed a sex-ratio of 1:2.1. A delayed maturation was recorded and lengths at sexual maturity (L ) were 20 and 17 cm TL for males and females, respectively. In Lake Ahozon, C. nigrodigitatus s pawned a l l s eas ons wi t h a p eak b et ween Apr i l - J une. B at ch f ecundities (F 50 ) ranged between 350-26040 eggs and significantly (p<0.05) increased with total length (F b = 0.314TL 3,023 b , r = 0.81) and body weight (F -203, r = 0.74). Egg diameters ranged between 0.30-3.10 mm and frequency distributions evidenced the production of multiple cohorts of eggs with an important stock of offsprings for recruitment. Chrysichthys nigrodigitatus di spl ayed a l i fe hi story strategy cl oser to “ k” sel ected that favored its propagation in Lake Ahozon. Conclusion: It is concluded that C. nigrodigitatus is a multiple spawner that reproduces all seasons in the man-made lake, with a peak in wet periods, April-June. The reproductive traits depicted in this special medium- environment are useful for fisheries management, aquaculture and species conservation.