The exercise stimulates the growth and muscular composition of the gilthead sea bream

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By Milthon Lujan

Gilthead sea bream. Source: CSIC
Gilthead sea bream. Source: CSIC

Are you looking for ways to optimize growth and health on your gilthead sea bream farm? New research suggests that incorporating exercise along with strategic dietary adjustments can change the game in gilt-head bream marine aquaculture.

The aquaculture food industry is constantly evolving, seeking to balance fish growth with sustainable practices. A key challenge is reducing reliance on marine ingredients in fish feed. While plant-based alternatives offer a solution, excess carbohydrates in carnivorous fish diets can be detrimental.

A team of scientists from the University of Barcelona published an article exploring the combined effects of swimming activity (voluntary swimming vs. exercise) and diet composition (high-protein diet vs. high-carbohydrate diet) on growth performance, muscular composition, meat texture, and gene expression in gilt-head sea bream juveniles (Sparus aurata).

The challenge of replacing proteins with carbohydrates

Protein is vital for fish growth, but carbohydrates are a cost-effective alternative. However, carnivorous fish like gilt-head sea bream have limited ability to utilize carbohydrates, which could lead to:

  • Poor growth
  • Excessive fat deposition
  • Health issues

Research suggests that sustained exercise can improve how gilt-head sea bream utilize nutrients:

  • Increases energy demand: Excess sugars in the diet are burned for energy, saving proteins for growth.
  • Improves protein utilization: Exercise can mitigate the negative effects of high-fat diets, promoting the use of proteins for growth.
  • General benefits: Exercise can lead to: Better feed conversion, Enhanced growth, Improved stress management, and Stronger immune system.
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The power of movement: exercise makes a difference

The study compared voluntary swimming (low activity) with sustained exercise and revealed that sustained exercise significantly improved growth in gilt-head sea bream juveniles compared to those with limited activity. It wasn’t just about weight gain but also about better utilization of diet nutrients.

Fish in the exercise group showed impressive results, including:

  • Improved growth performance: Fish subjected to regular exercise showed a significant increase in final body weight compared to those with less activity.
  • Leaner muscle mass: Exercise contributed to a reduction in muscle lipid content. This translates to healthier fish with a more desirable lean muscle composition.
  • Reduction in fat reserves: Exercise also led to a decrease in mesenteric fat (abdominal fat) and hepatosomatic index (liver size relative to body weight), indicating a reduction in overall body fat reserves.

Protein power

Here’s where things get interesting. When exercised fish were fed a high-protein diet, they reached the highest final body weight. This suggests that exercise creates an ideal environment for proteins to be used for muscle growth, leading to superior performance.

Fish fed a high-protein diet along with exercise showed the most spectacular growth:

  • Muscle development boost: High-protein diet, especially for exercised fish, increased the expression of genes related to muscle growth and development.
  • Enhanced metabolism: Gene expression analysis revealed improved anabolic state, suggesting that fish were using nutrients more efficiently to grow.

Gene expression takes center stage

Researchers delved deeper by analyzing gene expression, the cellular language that controls growth. They found that exercise, particularly when combined with a high-protein diet, significantly increased levels of genes involved in the growth hormone (Gh)/insulin-like growth factors (Igfs) axis. This hormonal pathway plays a key role in muscle development, and its activation explains the improvements observed in growth.

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Unexpected finding

A surprising result was the observed decrease in some meat texture parameters, particularly elasticity, in exercised fish. Further research is needed to understand this effect.

Importance for gilt-head sea bream aquaculture

This study highlights the powerful combination of exercise and a high-protein diet for promoting healthy growth and fat reduction in gilt-head sea bream. These findings can be valuable tools for optimizing aquaculture practices:

  • Formulating protein-adjusted diets: Tailoring diets to protein content based on activity levels can maximize growth and health benefits.
  • Promoting sustainable aquaculture: Exercise protocols can be implemented alongside proper nutrition for efficient and healthy fish farming.


Overall, this study underscores the remarkable benefits of exercise for gilt-head sea bream aquaculture. By incorporating strategic exercise routines and optimizing protein intake, fish farmers can achieve superior growth performance and potentially improve the quality of the final product.

Just like us, gilt-head sea bream thrives on a balance of exercise and a balanced diet. By incorporating this knowledge, aquaculture can produce healthier, faster-growing fish while promoting sustainable practices.

The study was funded by the Ministry of Science and Innovation/State Research Agency.

Isabel García-Pérez
Department of Cell Biology, Physiology and Immunology, Faculty of Biology, University of Barcelona, Barcelona, Spain
Email: isabelgarcia@ub.edu

Reference (open access)
García-Pérez, I., Montblanch, M., Sánchez-Moya, A., Perelló-Amorós, M., Otero-Tarrazón, A., Fernández-Borràs, J., Blasco, J., & Gutiérrez, J. (2024). Sustained exercise improves growth performance and reduces fat deposition in gilthead sea bream juveniles fed with a high-protein and a high-carbohydrate diet. Aquaculture, 740956. https://doi.org/10.1016/j.aquaculture.2024.740956