水産養殖研究開発ジャーナル

概要

Hematological and Histopathological Changes in Artificially Infected Nile tilapia with vibrio species

Begonesh Bekele, Natarajan P, Kassaye Balkew Workagegn, Devika Pillai

Bacterial pathogens such as vibrio species cause a significantly high economical loss in the aquaculture sector. Thus, the main objective of this study was to isolate and identify Vibrio species and evaluated the hematological, biochemical, and histopathological changes in experimentally infected Nile tilapia with 0.1 ml of 1×10⁶ colonyforming units (CFU)/ml of Vibrio species isolates. The clinical examination of the infected Nile tilapia revealed all fish became less active and the feeding rate decreased, the dorsal portion of the body became darkened. Fin rot appeared especially at the tips of the caudal fin and showed extensive hemorrhages at the ventral body part. The results also showed reduction in hemoglobin, hematocrit, protein, albumin, glucose, globulin, and triglyceride contents in the infected fish than the control group. The major histopathological changes noticed were inflammatory lesions, hemorrhagic dermis and melanomacrophage aggregation in the skin; hepatocellular degeneration, melanomacrophage aggregation, and nuclear hypertrophy in the liver; hypertrophy and fusion of different gill lamellae; myofibril disintegration and necrosis in the muscle tissue; and sub-mucosal oedema and atrophy in the intestine. In conclusion, experimental infection of fish with vibrio bacteria produced significant changes in clinical, hematological, biochemical and histopathological characteristics of Nile tilapia, in which the vibrio bacteria caused significantly high tissue damage and found to be severe in all the tissues examined. Therefore, it is important to develop strategies to control such pathogenic bacteria in order to achieve a sustainable fish production under a wide range of production environments.