Salmon lice, Lepeophtheirus salmonis and Caligus rogercresseyi, represent a major management challenge in salmonid aquaculture, imposing substantial economic losses primarily through repeated pharmacological treatments and handling events that induce physiological stress, increase susceptibility to secondary infections, and compromise growth performance. The progressive depletion of effective antiparasitic treatments, driven by escalating resistance, environmental concerns, and animal welfare constraints causing economic losses, has created an urgent need for sustainable alternatives in salmon lice management.
This study examined the integrated botanical effects and host physiological responses of Rosseus Plus��, a phytogenixc drinking supplement, administered via therapeutic baths and waterborne exposure against Lepeophtheirus salmonis and Caligus rogercresseyi under both controlled in vitro conditions and commercial-scale field trials in Atlantc salmon.
Controlled in vitro bioassays employing lice motility and responsiveness as early-stage screening endpoints, alongside field trials utilizing wellboat delivery, were conducted to characterize ectoparasitic burden dynamics across developmental stages. In vitro assays demonstrated 93–100% efficacy against adult Caligus rogercresseyi and Lepeophtheirus salmonis, respectively, while field trials employing achieved parasite reductions of 98% in adults and 85% in juveniles.
Molecular, histological, and physiological analyses collectively demonstrated systemic attenuation of acute and chronic stress responses, oxidative stress mitigation, and significant reduction of gill and skin inflammatory infiltration. Treated fish exhibited preserved neuroendocrine homeostasis, evidenced by stable cortisol profiles, maintained lysozyme activity, uncompromised innate immune function, balanced osmoregulation, and consistent serotonin concentrations. Waterborne administration of Rosseus Plus�� potentiated innate immune responses, attenuated key stress biomarkers, and enhanced feed intake and growth performance. The integration of antioxidant, serotonergic, and immunological biomarkers within a comprehensive multi-parametric analytical framework established a scientifically rigorous and reproducible platform for precision monitoring of host resilience, welfare, and treatment outcomes in intensive aquaculture systems.
These findings support Rosseus Plus�� as a safe, effective, and environmentally sustainable solution for integrated parasite management in Atlantic salmon aquaculture, promoting welfare-focused and responsible production practices.