Striped Pangasius catfish (Pangasianodon hypophthalmus) dominates finfish aquaculture production in Vietnam. Farmed mainly in the provinces of Dong Thap, Can Tho and An Giang in the Mekong Delta, this export oriented industry grew rapidly from 93 thousand tons in 2000 to 1.2 million tons in 2012; a levels of production that was maintained in 2018. The combination of intensive production in open farming systems, i.e. influent and effluent water sources are frequently shared and directly used by several adjacent grow-out farms has been linked to frequent disease outbreaks and high mortality rates, mainly of bacterial aetiology. Bacillary Necrosis of Pangasius (BNP) and Motile Aeromonad Septicaemia (MAS) were the most common and economically the most serious diseases experienced by nearly all catfish farmers. Small-scale grow-out farmers reported 1 to 10 episodes per crop whilst large-scale farmers reported 1 to 5 episodes per crop (mean 3.04). Antimicrobial treatments for 5-7 days are common practice. Amoxicillin, doxycycline, florfenicol and mixture of sulfamethoxazole and trimethoprim are used to treat BNP and MAS.
Thus, innovative approaches include investigating the effectiveness of the mode of application of the vaccine (i.e. immersion instead of manual injection), the alternative replacement of antimicrobials with immune stimulants and the development of fish health management approaches at a regional level (a zonal approach) are needed. In order to enhance the effectiveness of antimicrobials used in disease treatment, antimicrobial therapy for striped catfish should be rationalized. This should be done by evaluating and building up an antimicrobial susceptibility database, and by investigating the pharmacokinetics and pharmacodynamics of common antimicrobials used in striped catfish, e.g. by experimentation and/or by developing modelling approaches that allow extrapolations between different production practices and treatment regimes.