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Beta-carotene to enhance immunity and growth in tilapia fry

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By Milthon Lujan

Nile tilapia. Source: Sanipes
Nile tilapia. Source: Sanipes

The global demand for fish is increasing, driving aquaculture to ramp up production. However, cramming more fish into tanks can have drawbacks. While it seems like a good way to boost yields, high population density can lead to stressed fish and increase the risk of disease outbreaks.

Scientists are researching how to maintain high productivity in aquaculture without compromising fish health. Their approach? Natural immunostimulants like β-carotene derived from Spirulina platensis.

A team of researchers from Benha University, the Aquaculture Division of the National Institute of Oceanography and Fisheries (NIOF), Banha University, and Ateneo de Manila University conducted a study to evaluate the influence of dietary incorporation of β-carotene derived from Spirulina platensis (diets of 0, 0.5, and 1.0 g kg-1) on growth performance, feed efficiency, hematobiochemical indices, immune responses, and hepatic antioxidant enzymes and expression of associated immune-antioxidant genes in Nile tilapia Oreochromis niloticus fry raised at two population densities.

This article explores how a natural dietary supplement, β-carotene from Spirulina platensis, can significantly enhance the health and performance of Nile tilapia fry.

The challenge of ideal density

Stocking density is a balancing act. It directly affects fish survival, growth, behavior, health, and even water quality. While increasing density may boost production and income, it can also stress fish, leading to:

  • Poor growth: Studies show that fish in crowded environments often have reduced body weight.
  • Weakened immune system: High density can leave fish susceptible to diseases and infections.
  • Oxidative stress: Crowding can increase a fish’s metabolic rate, leading to cellular damage.
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The power of Spirulina

β-carotene, a natural pigment found in Spirulina platensis, shows promise as a way to mitigate the negative effects of high population density.

The main benefits of β-carotene are:

  • Boosts immunity: β-carotene acts as a natural immunostimulant, potentially helping fish fight infections and diseases.
  • Combat stress: By enhancing antioxidant activity, β-carotene can help fish cope with the stress of crowded conditions.

This study investigated the effects of adding different levels of β-carotene derived from Spirulina to tilapia diets. The results were promising!

Key findings

The main results of the study were:

  • Improved growth performance: Tilapia fed diets containing β-carotene, especially at a level of 0.5 g/kg, showed increased weight gain, final body weight, and improved feed conversion compared to those without supplementation, particularly at higher population densities (200 fish per cubic meter).
  • Enhanced immune response: Supplementation with β-carotene significantly stimulated the fish’s immune system. Levels of crucial blood proteins for immunity (C3, C4, and IgM) increased in fish fed β-carotene at both population densities.
  • Increased antioxidant defense: β-carotene acted as a powerful antioxidant, reducing harmful free radicals in the fish’s liver. This resulted in overall better health and stress resistance.

Dose optimization

The study found that the ideal amount of β-carotene supplementation varied depending on population density. Here’s a breakdown of the key findings:

  • Population density 100 (SD100): Diets containing 0.5 g/kg of β-carotene showed the most significant improvements in gene expression related to immune response.
  • Population density 200 (SD200): Higher levels (1.0 g/kg) of β-carotene resulted in the best overall growth performance, improved antioxidant activity, and increased production of immune proteins.
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Benefits for fish farmers

Supplementing tilapia feed with β-carotene from Spirulina offers several advantages for fish farmers:

  • Healthier fish: Enhanced immunity leads to fewer diseases and higher survival rates.
  • Faster growth: Faster-growing fish translates to quicker harvest cycles and greater profitability.
  • Reduced antibiotic dependency: By strengthening fish’s natural defenses, the need for antibiotics can be minimized, promoting sustainable practices.

Conclusion

This study provides robust evidence of the positive impact of Spirulina-derived β-carotene on Nile tilapia health. Further research can explore optimal β-carotene levels for other fish species and investigate potential economic benefits for fish farms.

Overall, this study offers valuable insights into the potential of Spirulina as a powerful natural health stimulant for tilapia aquaculture. Additionally, it’s important to highlight that tilapia aquaculture effluents can be utilized for Spirulina cultivation.

Contact
Eman Y. Mohammady
Aquaculture Division, National Institute of Oceanography and Fisheries, NIOF, Egypt
Email: dreman2529@gmail.com

Mohamed S. Hassaan
Department of Animal Production, Fish Research Laboratory, Faculty of Agriculture at Moshtohor, Benha University, Benha 13736, Egypt
Email: Mohamed.hassaan@fagr.bu.edu.edu.eg

Reference (open access)
Elashry, M. A., Mohammady, E. Y., Soaudy, M. R., Ali, M. M., El-Garhy, H. S., Ragaza, J. A., & Hassaan, M. S. (2024). Growth, health, and immune status of Nile tilapia Oreochromis niloticus cultured at different stocking rates and fed algal β-carotene. Aquaculture Reports, 35, 101987. https://doi.org/10.1016/j.aqrep.2024.101987