The global aquaculture industry has grown exponentially in recent years, leading to an increase use of to a variety of veterinary drugs (VMP) for the control of infections and diseases, which have different routes of emission, environmental persistence and side effects to aquatic organisms, becoming one of the main concerns in its use of VMP and its potential toxicological impact on the environment. The ecological risk assessment of the most commonly used active principles in freshwater salmonid fish farms worldwide were investigated and a priority list of active ingredients requiring further research on their potential effects and environmental concentrations was defined. We recollect a physical - chemical properties of active principles used by fish farms and we could estimate the relative hazard a priori. Later active principles grouped as antibiotics (oxytetracycline, flumequine, erythromycin, oxolinic acid and amoxicillin,), antiparasitics (emamectin benzoate, lufenuron, bronopol, formaldehyde and sodium chloride), anesthetics (isoeugenol, tricaine methanesulfonate and benzocaine), and disinfectants (glutaraldehyde, phenol, sodium hypoclorite and iodine) were assessed using a mass balance model based on fugacity was developed for each active principle under treatments via immersion and food administration in fish, while a volumetric model for disinfectants and sodium chloride was used for estimating the predicted environmental concentration (PEC), under a real smolt farming scenario in fish farms. Ecotoxicological data were collected from open literature to predict the no-effect concentration (PNEC). The ecological risk assessment was characterized using a risk quotient (RQ = PEC/PNEC) based in two assessment tiers. Results revealed that 12 active ingredients showed a high risk (RQ ≥ 1), thus indicating that adverse effects could occur and further investigation with measured concentrations in the field are required to reduce exposure in surface waters.