‘Lean’ and ‘fat’ trout facing fasting: two strategies revealed by a study published in Aquaculture

A study recently published in Aquaculture highlights the adaptation mechanisms of rainbow trout from two contrasting lines, ‘lean’ (low in lipids) and ‘fatty’ (high in lipids), subjected to a cycle of fasting followed by refeeding. This work is the result of a collaboration between the GeMS and GUPPIE teams at UMR GABI (Université Paris-Saclay, INRAE, AgroParisTech) and several INRAE partners from the PEIMA (Sizun) and IERP (Jouy-en-Josas) experimental units and the MARBEC laboratory (Univ. Montpellier, CNRS, Ifremer, IRD, INRAE). They explore the links between genetics, metabolism and immunity in trout. The researchers showed that the ‘lean’ line showed marked compensatory growth after refeeding, while the ‘fat’ line had greater weight loss during fasting and slower growth recovery. Certain metabolic and immune functions, measured by monitoring various blood parameters, remained altered after recovery, highlighting trade-offs between growth and physiological maintenance. These results contribute to a better understanding of the mechanisms of resilience in farmed fish when faced with stress, in this case nutritional stress.

This study paves the way for future multidisciplinary research conducted at the GABI unit, combining genetics, physiology and immunity in trout for an integrated approach to performance and robustness in aquaculture.

Scientific contact :

• Fany Blanc (Team GeMS)
• Simon Pouil (Team GUPPIE)

Reference :
Fany Blanc, Thierry Kernéis, Floriane Colon, Marjorie Bideau, Dimitri Rigaudeau, Nicolas Bruneau, Michaël Marchand, Isabelle Leguen, Simon Pouil. Growth, metabolic, and immune responses of lean and fat rainbow trout lines during a starvation-refeeding cycle. Aquaculture, Volume 612, Part 1, 2026, 743132, ISSN 0044-8486, https://doi.org/10.1016/j.aquaculture.2025.743132