Prevalence of Aeromonas hydrophila Isolates in cultured and Feral Clarias gariepinus of the Kainji Lake Area, Nigeria,

Abstract

Bacterial diseases especially those caused by Gram- negative organisms are responsible for mass mortality in both wild and cultured fish species. Aeromonas hydrophila is one of the Gram- negative bacteria commonly encountered in an aquatic environment. The prevalence of A. hydrophila the causative agent of aerornonad septicaemia of fish was investigated among the wild C. gariepinus caught from different sampling sites in Kainji Lake and cultured fish samples from homestead fish farms within the Kainji Lake area. Morphometric measurements were taken for each fish sample collected, isolation and identification of the bacteria using morphological characteristics and biochemical tests was carried out. Morphometric characteristics of the fish species shows that the mean condition factor (K) of the infected C. gariepinus was 1.09±0.15 while the uninfected was 1.81±0.14. The difference in K of infected and uninfected was statistically significant (p<0.05). Hemorrhages on the body surface, ulcers of various sizes on the skin, fin erosions, inflamed vent, abdominal distension and bulging eyes were some of the sign observed ill some of the fish samples that A. hydrophila was isolated. The bacteria was isolated from 19.2% of the wild C. gariepinus sampled while 30.5% from the cultured samples.

KEY WORDS: Prevalence, Aeromonashydrophila, morphometric Clarias gariepinus