Abstract

The aim of this study was to evaluate the efficacy of Hibiscus Rosa sinensis flowers and leaves hydroethanolic extracts on survival, growth and gonads development of Oreochromis niloticus. To this end, 840 fingerlings of Oreochromis niloticus with an average weight of 7.5 ±1.01g were randomly distributed in 21 tanks with a capacity of 40L each, placed in an earthen pond of approximately 150 m2 (fed by ground water), at a density of 40 fingerlings per tank. These different fishes were fed with 7 experimental feeds, including 01 control and 06 based on H. rosa sinensis leaves and flowers hydroethanolic extracts at doses of 100, 150 and 200 mg/kg of feed (for the leaves) and 100, 150 and 200 mg/kg of feed (for the flowers) respectively. After 45 days post-treatment, survival and zootechnical growth parameters were assessed. Histological examination of the gonads was used to determine the impact of the various treatments on gonads development at 45 and 60 days post-treatment respectively. The results showed that the dose of extract did not significantly affect fish’s mortality. Analysis of the growth parameters of fishes from the different group treated with different doses of H. Rosa sinensis leaves and flowers hydroethanolic extracts revealed that the dose of 100mg/kg of H. rosa sinensis leaves extract had a greater significant effect compared with the other treatments applied. Analysis of the Gonado-somatic index at 45 days post-treatment revealed significantly (p <0.001) lower gonad weight/mass ratios in males treated with the various doses of H. rosa sinensis leaves and flowers hydroethanolic extracts compared with sample from control group ( 0.415 ± 0.031%). However, at 60 days post-treatment, satellite males from control group and those from group treated with 100mg/kg of flowers and leaves extract recorded a higher Gonado-somatic Index than the other treatments, with Mean values of 0.415 ± 0.022%, 0.431 ± 0.044% (FL’100) and 0.387 ± 0.016% (LE’100) respectively. On the other hand, in females, those treated with a dose of 200mg/kg of flowers recorded a higher Gonado-somatic Index than the other treatments, with a mean value of 1.34 ± 0.37%. Observation at 45 days post-treatment of the testicular structures of males from group treated with extracts showed a dose-dependent alteration in spermatogenesis marked by destruction of spermatozoa. However, in satellite males from group treated with 100 mg/kg of H. rosa sinensis leaves and flowers hydroethanolic extracts, spermatozoa were restored. In satellite females, the integrity of ovarian tissue was only restored in females treated with 100mg/kg of H. Rosa sinensis leaves and flowers hydroethanolic extracts.