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Introduction

Nile tilapia (Oreochromis niloticus) is one of the world’s most widely farmed fish species due to its rapid growth, efficient feed utilization, adaptability to diverse production systems, and broad consumer acceptance (El-Sayed, 2006).

One of the major production challenges in commercial tilapia farming is early sexual maturation. Mixed-sex populations reproduce before harvest, resulting in excessive stocking densities, increased competition for feed, reduced growth uniformity, and lower harvest weights, ultimately decreasing production efficiency (El-Sayed, 2006).

To overcome this challenge, commercial hatcheries have traditionally relied on dietary administration of 17α-methyltestosterone (MT) during early larval development to produce predominantly male populations. Male tilapia generally exhibits faster growth, improved feed efficiency, and greater harvest uniformity than females, making masculinization an established management practice in intensive aquaculture (Pandian & Sheela, 1995; Beardmore et al., 2001).

However, increasing regulatory scrutiny, environmental considerations, and growing consumer demand for hormone-free aquaculture products have stimulated interest in alternative production strategies. Among these, phytogenic feed additives have emerged as promising nutritional tools because they can improve nutrient utilization, digestive efficiency, antioxidant capacity, immune competence, and overall production performance through naturally occurring plant bioactive compounds (Citarasu, 2010; Dawood et al., 2018; Reverter et al., 2014; Singh et al., 2024).

Tilandrone is a proprietary phytogenic feed additive developed as a hormone-free nutritional strategy for Nile tilapia production. This article summarizes the findings of a controlled in vivo study evaluating its effects on growth performance, feed efficiency, and masculinization compared with conventional MT treatment.

Study Design

A controlled feeding trial was conducted using specific pathogen-free (SPF) Nile tilapia in Vietnam. The experiment consisted of a 43-day nursery phase followed by a 76-day grow-out phase. Five dietary treatments were evaluated: an untreated control, MT (60 mg/kg feed), and Tilandrone at 200, 400, and 800 mg/kg feed. During grow-out, treatments were evaluated in four replicate hapas per treatment that were randomly distributed. Production performance was assessed using final biomass, final body weight, biomass gain, average daily gain (ADG), Feed Conversion Ratio (FCR), and sex reversal rate.

Scientific Background

Producing predominantly male tilapia populations remains one of the most effective approaches for improving commercial productivity because males generally exhibit superior growth and production efficiency compared with females (Beardmore et al., 2001; El-Sayed, 2006).

Although MT remains the industry standard for masculinization, concerns regarding sustainability, regulatory acceptance, and consumer perception have encouraged the development of hormone-free alternatives.

Phytogenic feed additives have attracted increasing attention because numerous studies have demonstrated their ability to improve digestion, feed utilization, antioxidant status, immune response, and growth performance in cultured fish species (Citarasu, 2010; Dawood et al., 2018; Reverter et al., 2014; Alagawany et al., 2025).

Unlike synthetic hormones, phytogenic formulations do not provide exogenous steroid hormones but may influence multiple physiological pathways through naturally occurring plant metabolites. Their potential contribution to masculinization, however, remains an emerging field requiring well-designed in vivo validation.

Potential Mechanisms of Action

Unlike MT, which directly influences sex differentiation through androgenic activity, phytogenic formulations are believed to modulate endogenous physiological processes.

The improvements observed in growth performance, feed efficiency, and male ratio suggest that Tilandrone may influence nutrient utilization, metabolic efficiency, and developmental regulation simultaneously. Similar multifunctional responses have been described for phytogenic feed additives in aquaculture, although the specific biological mechanisms depend on the composition of the formulation and the target species (Dawood et al., 2018; Singh et al., 2024).

The precise mechanisms responsible for the increased proportion of male fish remain to be elucidated. Future studies investigating endocrine responses, gene expression, and molecular signaling pathways will contribute to understanding the biological basis of these observations.

Results

Growth performance

Growth performance improved consistently in fish receiving Tilandrone supplementation.

FCR

Feed represents the largest operating cost in commercial aquaculture, making FCR one of the most important indicators of production efficiency.

Under the conditions of this study, Tilandrone generated a higher proportion of male fish than the MT treatment. Because MT efficacy is influenced by larval age, treatment duration, feed preparation, genetics, and environmental conditions, these findings should be interpreted within the context of the present experimental conditions (Pandian & Sheela, 1995; Beardmore et al., 2001).

Practical Relevance

The 200 mg/kg inclusion level consistently produced the greatest improvements in growth performance, whereas 400 mg/kg achieved the highest male ratio. Together with the observed improvements in feed efficiency, these findings suggest that phytogenic nutrition may provide benefits extending beyond masculinization alone.

As with any nutritional intervention, responses are expected to vary according to genetics, hatchery management, environmental conditions, feed formulation, and production system.

Conclusion

This controlled in vivo study demonstrates the potential of Tilandrone as a hormone-free nutritional strategy for Nile tilapia production.

Compared with the untreated control, Tilandrone improved growth performance, feed efficiency, and the proportion of male fish. The greatest growth response was achieved at 200 mg/kg, whereas 400 mg/kg produced the highest male ratio (85%) under the conditions of this study. Although additional validation under diverse commercial production conditions is warranted, these findings suggest that phytogenic nutrition may reduce reliance on conventional hormone-based masculinization while supporting productive performance in Nile tilapia culture.

References

1. Alagawany, M., et al. (2025). Phytogenic feed additives as a sustainable alternative to improve growth performance and health in Nile tilapia. Animals, 15(3), 380.
2. Beardmore, J. A., Mair, G. C., & Lewis, R. I. (2001). Monosex male production in finfish as exemplified by tilapia: Applications, problems, and prospects. Aquaculture, 197(1–4), 283–301.
3. Citarasu, T. (2010). Herbal biomedicines: A new opportunity for aquaculture industry. Aquaculture International, 18, 403–414. https://doi.org/10.1007/s10499-009-9253-7
4. Dawood, M. A. O., Koshio, S., & Esteban, M. Á. (2018). Beneficial roles of feed additives as immunostimulants in aquaculture: A review. Reviews in Aquaculture, 10(4), 950–974.
5. El-Sayed, A.-F. M. (2006). Tilapia culture. CABI Publishing.
6. Pandian, T. J., & Sheela, S. G. (1995). Hormonal induction of sex reversal in fish. Aquaculture, 138(1–4), 1–22. https://doi.org/10.1016/0044-8486(95)01075-0
7. Reverter, M., Bontemps, N., Lecchini, D., Banaigs, B., & Sasal, P. (2014). Use of plant extracts in fish aquaculture as an alternative to chemotherapy: Current status and future perspectives. Aquaculture, 433, 50–61.
8. Singh, A., et al. (2024). Exploring phytobiotics in aquaculture: Sources, mode of action, and therapeutic effects in fish. Aquaculture International.

Author: Tsvetelina Ilieva, VEMO Corp.