Occurrence of bacterial infection in two commonly cultured fish species on two fish farms in southern Ghana
Bacterial infection in fish is very important to the fish, the fish farmer and the consumer. The study evaluated the presence of pathogenic and non-pathogenic bacterial species in cultured Oreochromis niloticus and Clarias gariepinus. A total of Fifty-five (55) individuals O. niloticus and C. gariepinus with weight between 14.1 to 389.5 g and standard length between 7.0 to 35.4 cm were sampled from two farm at Ashaiman and Akosombo for the examination of presence of pathogenic bacteria in their tissues. Tissues from the gill, stomach and liver were excised under aseptic conditions. These were inoculated in Brain Heart Infusion broths (BHI) and incubated for 24 hours at 37 °C then subsequently streaked on MacConkey Agars and Blood Agars (Supplemented with 5 % sheep blood). The MacConkey and Blood Agars were also incubated for 24 hours at 37 °C. Bacteria colony that grew on the MacConkey and Blood Agars were picked with an inoculation loop and taken through a series of standardized test for bacteria identification. The test used were gram staining and biochemical test such as Indole, Catalase, Oxidase, Urease, Simmons Citrate and Sulphur Indole Motility tests. Bacterial species belonging to the genus Shigella, Streptococcus, Klebsiella, Pasteurella, Neisseria, Edwardsiella, Bacillus, Pseudomonas, Staphyloccocus, Yersinia, Enterobacter,Citrobacter, Escherichia, Flavobacterium, Streptobacillus, and Proteus were isolated from the two fish species sampled from the two sites. The presence of these pathogens means the potential outbreak of serious fish disease exists for fish farms, consumers in Ghana and worldwide.