Isolation of Aeromonas hydrophila and Evaluation of Its Pathological Effects on Koi Fish (Cyprinus carpio)

Abstract

In the summer of 2018, this study was performed on 50 Koi fish transferred to Razef Research Complex. In this study, after observing macroscopic symptoms in fish, including lethargy and immobility, imbalance, darkening of the skin, skin wounds, petechiae in the abdomen, opacity of the eye and anophthalmia, anorexia, and sitting on the bottom of the aquarium, sampling was performed to diagnose the pathogens and examine the pathological changes. According to microbial tests on skin samples and internal organs, Aeromonas hydrophila was reported, and septicemia in 48% of the studied fish. In necropsy specimens, the organs were pale, the liver was enlarged, and petechiae were observed on the surface of the liver. The microbial contamination also led to considerable tissue damages, including the destruction of gill filaments, nuclear pycnosis in the liver, and the infiltration of inflammatory cells into the heads of all fish. Considering the significant losses due to the pathogenicity of Aeromonas hydrophila in different fish species and the importance of Koi fish, observing quarantine and hygienic principles to prevent sepsis was very important. Early diagnosis and use of appropriate treatment protocols for this disease are recommended.

The potential of bitter melon extract on cellular non-specific immunity of koi fish (Cyprinus carpio) after Aeromonas salmonicida infection

“…The rate of bacterial attack on fish hatcheries can occur within a few hours. Bacterial attacks by A. salmonicida destroy the internal organs of fish fry and skin wounds (Parvez and Mudarris 2014;Alavinezhad et al 2021). The ability of A. salmonicida to infect fish is related to the bacteria's ability to produce toxins (Soni et al 2021).…”