The efficacy of using pine (Pinus massoniana) pollen as an alternative to synthetic steroids in producing monosex male Nile tilapia (Oreochromis niloticus, L.)

Abstract Synthetic sex steroids are widely used to produce all‐male stocks in Nile tilapia (Oreochromis niloticus). However, there is a growing concern about the use of synthetic steroid hormones in fish as food. We investigated the efficacy of a natural sex hormone as an alternative to synthetic steroids in producing monosex male tilapia. Two‐day‐old fry were fed pine pollen powder at three different concentrations (0.5%, 1.0%, 1.5%) for 28 days and subsequently reared for 3 months to observe the efficacy of pine pollen as well as to optimize the concentration for sex reversal. As a positive control, same‐aged fry of three different commercial tilapia hatcheries were fed synthetic steroid and 17‐α‐methyl testosterone‐treated feed (60 mg/kg) for the same duration. Before analyzing the phenotypic sex, the fish were reared on untreated commercial feed for 90 days in separate tanks. The 1.0% pine pollen treatment yielded a mean of 92.50 ± 0.51% males among the progeny, higher than the mean (89.49 ± 0.25%) obtained from synthetic steroid treatments. This result demonstrates that pine pollen could be an effective compound for the direct masculinization of Nile tilapia. We also obtained a significant difference (p < 0.05) in the growth performance and survival of tilapia using the dietary allotment of pine pollen. Our study suggests the feasibility of this compound as an eco‐friendly method of masculinization of tilapia and can be tried in commercial aquaculture practice.