Effect of bacteriophages against aeromonas hydrophila infections in tilapia oreochromis niloticus fingerlings and juvenile held in aquaria tanks

Abstract

This study assessed the effect of bacteriophages on Aeromonas hydrophilia infections in farmed fingerlings and juvenile tilapia fish group. The host bacteria (Aeromonas hydrophila) were revived and confirmed using biochemical tests while the bacteriophage was bulked up using standard methods and enumerated using overlay agar method. Fish were conditioned prior to transportation and acclimatized in tank water before stocking in experimental tanks to minimize stress and mortalities. The acclimatized fish were separated into test and control subjects. Test fish were treated with bacteriophages and observed for mortality for 14 days. The control group were inoculated with neither bacteria nor phages. The results showed that bacteriophages are stable at pH range of 6-9. A multiplicity of infection (MOI) of 10 and 100 showed efficacy. Similarly, mortality rate recorded by the 7th day was low at 40% among the treatment group compared to 100% among the control (untreated). It is recommended that the pH range of 6-9 is suitable for effective infectivity of the bacteriophage, bathing method is an efficient route for administration and the MOI of 10 is an efficient dose to treat Aeromonasis in fish tanks. However further study is required to determine its applicability and validate the use of bacteriophage out of the tank.