Effects of supplementary fennel (Foeniculum vulgare) essential oil in diet on oocytes maturity and sexual maturation of Convict cichlid (Cichlasoma nigrofasciatum)

In this study, the effects of supplementary fennel (F. vulgare) essential oil on oocytes maturity and sexual maturation of Convict cichlid (C. nigrofasciatum) were investigated. For this purpose, 225 Convict cichlids with mean weight (1.65±0.02 g) were distributed into 80-l glass aquaria (15 fish/tank) in triplicate treatments and fed with diets containing levels of fennel essential oil at 0, 100, 125 and 150 mg kg-1, at 3% of their body weight daily for 40 days. Results of gonad histology (30 days after fed), time to sexual maturation and the elapsed time from mating to spawning showed that most oocytes of control, 75 and 125 mg essential oil groups being in pronuclear stage and some of them in vitellogenesis. In 100 and 150 mg essential oil treatments, most oocytes were observed in final stage of vitellogenesis and as compared to other treatments had more evolution of maturity. The lowest time for sexual maturation observed in 150 mg essential oil (78±1.15 day) that had significant difference with control group and other treatments except 100 mg essential oil (p<0.05). The elapsed time from mating to spawning in control group (17.66±1.45 day) were longer as compared to all treatments fed with fennel essential oil (p<0.05).