Global aquatic animal production has increased substantially since 1950, reaching 185 million tonnes in 2022, with aquaculture contributing over 51% of total output. In Chile, Atlantic salmon (Salmo salar ) dominates the export-oriented aquaculture industry but faces major health challenges, especially caligidosis caused by the ectoparasite Caligus rogercresseyi . This parasite disrupts immune, neuroendocrine, and metabolic functions, reducing fish welfare and causing economic losses. Concerns over drug resistance, environmental impact, and animal welfare have driven interest in sustainable, non-pharmacological alternatives.
This study assessed the antiparasitic efficacy and physiological benefits of Rosseus Plus®, a botanical supplement based on essential oils and plant extracts, administered via therapeutic baths and water exposure. In vitro assays showed 93–100% effectiveness against adult C. rogercresseyi , while field trials using wellboats achieved parasite reductions of 98% in adults and 85% in juveniles. Waterborne delivery enhanced immune responses, lowered stress markers, and improved the intake of the feeding and the growth.
Molecular, histological, and physiological analyses revealed significant reduction in acute and chronic stress, mitigation of oxidative stress, lowering inflammation in gill and skin . Treated fish maintained stable cortisol levels, preserved lysozyme activity, uncompromised immune response , balanced osmoregulation and consistent serotonin concentrations, indicating improved neuroendocrine balance and welfare. The inclusion of antioxidant, serotonergic biomarkers provides a robust, science-based framework to monitor fish resilience and welfare, offering precise evaluation of health and treatment effects.
These findings support Rosseus Plus® as a safe, effective, and environmentally sustainable strategy for integrated parasite management in Atlantic salmon aquaculture, promoting welfare-focused and responsible production practices.