Fungal infections and flavobacteriosis are significant health challenges affecting Salmo salar in aquaculture systems, during freshwater phases. These pathogens can compromise fish welfare, cause lesions, and increase mortality if not promptly managed. Salt baths, Bronopol and Formaline are commonly used as a curative and preventive treatment, yet their impact on animal welfare remains underexplored. Understanding the effectiveness and welfare implications of such treatments is critical for sustainable fish health management. This study evaluated the effect on animal welfare and health of two conventional preventive and curative treatments in fresh water, Salt at 2%, Formalin at 150 ppm and 40 ppm of Bronopol with AQBiocare Plus®, a naturally formulation derived of plants with antimicrobial broad spectrum with antioxidant and anti-inflammatory properties. The in vitro and in vivo studies in Atlantic salmon demonstrated the antibacterial efficacy against key pathogens, including Flavobacterium and Saprolegnia. In vitro studies validated through absorbance and MIC assays that AQ Biocare Plus® shows strong antimicrobial activity lasting 24 to 48 hours during immersion treatments and on fungal the doses of inhibiting to Saprolegnia were 50 ppm.
Beyond its antimicrobial properties, AQBiocare Plus® enhances innate immune responses, and takes care of the production and quality of the skin mucus, promoting disease resistance. It significantly strengthens natural immunity by improving cutaneous, mucosal, and serum immune parameters while upregulating immune-related genes. At the molecular level, it enhances inflammatory, immune, antiviral, and antibacterial responses while mitigating oxidative stress by reducing and scavenging free radicals. The markers of anti-inflammatory AqBiocare showed a stable response (IL1b, IL10, TNFa,) and tissue remodeling indicators (Col1A1, MMP2, MMP13) suggested a reduced skin damage compared with Formaline and Salt. The formulation also demonstrates superior control over reactive oxygen species (ROS), resulting in reduced oxidative stress, with lower activity of NFEL2, SOD3, GPX, and CAT, alongside high lysozyme levels, indicating enhanced bacterial protection. Fish treated with AQBiocare Plus® showed improved physiological balance, with up to 25% lower cortisol and 18% lower glucose compared to Salt or Formalin. Welfare biomarkers remained stable even under smoltification stress, indicating enhanced stress resilience. Histologically, AQ Biocare Plus® increases mucous cell density in the skin, improves the quality and the quantity of the mucus, strengthening the fish’s natural barrier, it has better effect on Lizozime. Welfare analyses, including serotonin, cortisol, lactate, glucose and osmolality measurements, highlight its positive impact on fish well-being.
These comprehensive benefits position AQ Biocare Plus® as an innovative and sustainable alternative in salmon farming, effectively protecting fish health, enhancing productivity and improving animal welfare.