In the aquaculture sector, the larval stage represents a critical window of “physiological plasticity.” During this brief period, external stimuli can permanently reprogram the endocrine and structural pathways of fish—a phenomenon known as metabolic programming. A recent study published in the Journal of Animal Physiology and Animal Nutrition by researchers from the State University of Maringá (UEM) in Brazil has revealed how precise intervention during this stage can define the production success of Nile tilapia (Oreochromis niloticus).
The practice of hormonal sexual inversion, an industry standard for obtaining fast-growing all-male populations, has traditionally been analyzed in isolation. However, the team led by Jaisa Casetta and Stefania Claudino-Silva has demonstrated that aligning this hormonal stimulus with advanced functional nutrition—specifically microencapsulated bioactives—creates a synergy that redefines the species’ biological ceiling.
Key Highlights
- Winning Synergy: The combination of inversion hormones and microencapsulated supplements optimizes growth more effectively than either factor alone.
- Genetic Modulation: The nutritional supplement acts as a molecular switch, reducing the expression of myostatin (a growth inhibitor) to minimal levels.
- Oxidative Shielding: The microencapsulation of organic acids and essential oils drastically reduces cellular damage (protein carbonylation) in larvae.
- Intestinal Architecture: The protocol significantly increases intestinal villi height, maximizing nutrient absorption from the early stages.
The Experiment: Designing the Fish of the Future
To test this hypothesis, researchers used 2,400 GIFT strain tilapia larvae, starting at just 6 days post-hatching. The factored experimental design allowed for the comparison of four distinct scenarios over 28 days:
- NI (Non-Inverted): Control group without hormones or supplements.
- I (Inverted): Larvae treated with 17α-methyltestosterone for sexual inversion.
- NI+M (Supplemented): Non-hormonal larvae fed a microencapsulated blend of organic acids and essential oils (ENTERIFIN M300 FISH).
- I+M (Combined): The cutting-edge protocol merging hormonal inversion with microencapsulated supplementation.
Why microencapsulation?
Unlike conventional additives, microencapsulation protects compounds (such as carvacrol, thymol, and organic acids) from premature degradation, enabling a gradual release throughout the gastrointestinal tract. This is vital in larvae, where the digestive system is in full development.
Results: Beyond Mere Weight and Size
The Leap in Zootechnical Performance
The results were definitive: groups receiving sexual inversion (I and I+M) showed significantly higher weight gain at 14 and 28 days. Total length was also enhanced, peaking in the I+M group toward the end of the experiment.
Growth Modeling: Quality over Speed
Using mathematical models (Logistic and Gompertz), scientists identified fascinating patterns. The NI (control) group showed a “boom and bust” strategy: rapid initial growth that prematurely exhausted its developmental potential. In contrast, the NI+M group (supplement only) reached the highest theoretical growth asymptote, suggesting that functional nutrition alone can “rescue” growth potential even in non-inverted fish.
The Molecular Revolution: GH vs. Myostatin
The study delved into gene expression to understand the underlying drivers of these changes:
- Growth Hormone (GH): The highest levels were found in inverted groups (I and I+M), stimulating muscle anabolism.
- Myostatin (Mstn): This gene acts as a “brake” on muscle growth. The control group (NI) exhibited the highest expression of this inhibitor. Remarkably, microencapsulated supplementation succeeded in reducing myostatin expression to low levels, similar to those of hormone-treated fish.
Architecture of Efficiency: Intestines and Muscles
The growth improvement was not merely a matter of appetite but of structural reconfiguration. Histological analysis revealed that the I+M group possessed the highest intestinal villi of all treatments.
“The increase in villi represents an adaptation of absorptive capacity, ensuring a greater flow of nutrients into the organism.”
Simultaneously, muscle tissue showed coordinated expansion. The height and width of the dorsal muscle were maximized in the I+M group, translating nutritional efficiency into biomass deposition.
Stay Always Informed
Join our communities to instantly receive the most important news, reports, and analysis from the aquaculture industry.
Oxidative Stability: Less Stress, Better Health
One of the most relevant findings for animal welfare was the reduction of physiological stress. Control group larvae (NI) presented the highest levels of carbonyl proteins, a direct marker of oxidative damage. Microencapsulated supplementation significantly reduced this oxidative load, acting as a metabolic shield that allows the fish to channel energy toward growth rather than cellular repair.
Global Impact and Limitations
This study positions the I+M protocol as a precision intervention that maximizes return on investment in tilapia larviculture. It demonstrates that advanced nutrition is not just a cost, but a metabolic programming tool that optimizes health and performance.
The researchers note that while the 28-day results are promising, long-term studies are necessary to evaluate whether these benefits persist until the harvest stage and if they influence final fillet quality or reproductive capacity.
Reference (open access)
Casetta, J., Gasparino, E., Silva, C. I. da, Siemer, S., Cangianelli, G. H., Vasconcellos, R. S., Ribeiro, R. P., Mari, G. C., Roesler, J., Sofientini, J., Marques, D. de O., & Claudino-Silva, S. (2026). Endocrine-nutritional synergy between sex inversion and microencapsulated bioactives enhances growth, intestinal development, and oxidative stability in Nile tilapia larvae. Journal of Animal Physiology and Animal Nutrition, 1–12. https://doi.org/10.1111/jpn.70046
Editor at the digital magazine AquaHoy. He holds a degree in Aquaculture Biology from the National University of Santa (UNS) and a Master’s degree in Science and Innovation Management from the Polytechnic University of Valencia, with postgraduate diplomas in Business Innovation and Innovation Management. He possesses extensive experience in the aquaculture and fisheries sector, having led the Fisheries Innovation Unit of the National Program for Innovation in Fisheries and Aquaculture (PNIPA). He has served as a senior consultant in technology watch, an innovation project formulator and advisor, and a lecturer at UNS. He is a member of the Peruvian College of Biologists and was recognized by the World Aquaculture Society (WAS) in 2016 for his contribution to aquaculture.
