Prevalence of Streptococcus agalactiae in Hybrid Red Tilapia (Oreochromis sp.) From Inland Farm in Jeli, Kelantan

Tilapia is a worldwide cultured fish both in freshwater and brackish water, and known as aquaculture chicken as it is present in all continents except Antarctic. Major problems in local tilapia breeding are mostly related to improper management system and lack of biosecurity that could introduce the occurrence of diseases. The outbreak of Streptococcosis had been reported more than a decade ago but up until today it is still known as common cause of mortality in tilapia population thus resulting in economic loss. The aim of this study was to screen Streptococcus agalactiae from hybrid red tilapia, Oreochromis sp. by molecular techniques. Subsequently, the prevalence of S. agalactiae infection in tilapia captured from inland farm located in Jeli, Kelantan was investigated. Four samplings was conducted where ten fish was randomly collected respectively. The DNA extraction was done and then subjected to polymerase chain reaction (PCR) for S. agalactiae specific 16S rDNA detection. Following the PCR optimization, one well defined band was chosen indicating the perfect annealing temperature for the reaction at 52.8˚C. All samples obtained from sampling showed no clinical sign of S. agalactiae except for enlarged kidney which observed in some of the fish during necropsy. Aside from showing the clinical sign of usual Streptococcosis infection, no positive PCR result was obtained indicating that the fish is free from S.agalactiae infection.