The use of injectable oxytetracycline in aquaculture has been constrained by administration challenges and variable efficacy. In this study, we have analyzed 103 rainbow trout (Oncorhynchus mykiss) production cycles (2015 and 2025), to compare the efficacy of injectable oxytetracycline (OTC) versus oral antibiotic in managing piscirickettsiosis (SRS).
Results show that injectable formulation reduced total mortality rate by 20.3% and SRS-specific mortality by 58.1%, while cutting overall antibiotic use by 30.7%. Treated groups achieved a 20.9% higher final weight and 20.5% increase in yield (Fig.1) . The optimal application window was identified for fish weighing 0.5–1. 5 Kg; larger specimens had more mortality and required oral antibiotic (Fig . 2), reducing cost-effectiveness. Bioeconomic analysis revealed a 32% higher net profit with injectable administration, driven by enhanced survival and better yield.
These findings establish injectable OTC as a n effective, environmentally sustainable and economically viable standards for the management of SRS in trout farming. The protocol overcomes existing treatment barriers, aligns with responsible a quaculture standards (ASC/BAP), and provides a scalable, evidence-based solution for aquaculture operations.