BioMar presents experimental and farm results on a functional feeding strategy for European seabass

For Euroean seabass producers, the value of a nutritional strategy depends on whether its benefits can be demonstrated under farm conditions.

A study presented at Aquaculture Europe 2026 by Gabriela Carril Leiva, from Global R&D at BioMar Group, and colleagues addressed this question through two complementary assessments: a controlled bacterial challenge and monitoring at a commercial farm during a period of heightened disease risk.

The first trial involved European seabass juveniles weighing 21 grams, fed for seven weeks before an immersion challenge with Photobacterium damselae subsp. piscida at 22ºC. The researchers compared a control diet with a diet incorporating a functional blend of additives and microingredients.

The field assessment extended the comparison to a commercial grow-out farm. The trial involved more than 1.6 million seabass across seven sea cages – three receiving the control diet and four the functional feed – with an initial fish weight of approximately 185 grams.

Monitoring took place from August to November, a period identified by the authors as carrying a high risk of bacterial outbreaks.

Under commercial conditions, the researchers found a 47% relative reduction in mortality compared with the control. This provides evidence to help producers plan functional feeding strategies to support fish resilience to pathogens at farm level, building on previous results obtained under controlled conditions.

As Gabriela Carril explains misPeces, functional diets should not be viewed as a reactive response to an established health problem. They allow producers to prepare for periods of heightened disease risk, helping to strengthen fish resilience when it is most needed.

They are not a standalone solution, but can add value when used as a planned way and combined with good management of fish health and the farming environment.

Their greatest potential is realised when they are introduced before the risk window, ahead of periods when bacterial pressure has historically been higher.