Synthetic 17α-methyltestosterone use for monosex tilapia production is increasingly restricted on environmental and food-safety grounds, creating demand for non-synthetic, hormone-free alternatives. This study evaluated four isonitrogenous, black soldier fly larvae (BSFL)-based diets containing a ten-herb Chinese herbal extract (CHE) mixture (Sigesbeckia orientalis, Codonopsis pilosula, Citrus aurantium, Citrus sinensis, Aquilaria sinensis, Commiphora myrrha, Eclipta prostrata, Juglans nigra, Ligusticum chuanxiong and Cistanche deserticola) at 0 (control), 0.5, 1.0 and 1.5% inclusion, fed to Nile tilapia, Oreochromis niloticus (Linnaeus, 1758), broodstock and progeny across three generations (F0-F1, F1-F2, F2-F3) in earthen clay ponds in Selangor, Malaysia. All three CHE-supplemented diets progressively shifted the population from a near-balanced sex ratio at F0-F1 to a fully monosex, all-male population by F2-F3, whereas the unsupplemented control remained 42.6-43.9% male throughout. The 0.5% inclusion level produced the highest cumulative male output (538.7 fish; 75.3% of total growers), the best egg-to-grower survival (78.7% by F2-F3) and the most efficient feed conversion ratio (FCR) (1.24-1.27), and, among the CHE treatments, provided the most favourable overall combination of survival, feed efficiency, male output and water-quality parameters. We conclude that 0.5% dietary CHE inclusion is the most biologically effective and economically efficient dose for hormone-free, multigenerational, all-male O. niloticus production in earthen clay-pond systems typical of smallholder and commercial tropical aquaculture.
