Abstract:
Streptococcus spp. is one of the most significant diseases in tilapia culture worldwide
and particularly in indoor system. Streptococcus spp. is the largest problem in intensive
tilapia rearing systems throughout the world. Streptococcal infections in fish result in
septicemic diseases that have been reported worldwide causing severe economic losses
in fish production. This study was conducted to isolate and identify the Streptococcus
spp. from red tilapia (Oreochromis niloticus). In this present study, a total of 127 red
tilapias ( Oreochromis niloticus) were caught in tilapia cage culture in Sungai Manir
(Terengganu), Sungai Arau (Perlis), Sungai Kodiang (Kedah), Sungai Tunjang (Kedah)
and Aquaculture Development Centre, Jitra, Kedah. The fishes then were dissected and
the organs of brain, eye and kidney were streaked directly on Blood Agar (Merck,
Germany) containing 5% of human blood. The bacterial colonies then were subcultured
on TSA media (Merck, Germany) to get the pure colony. The gram staining process was
carried out to all isolates and only five out of 127 isolates turned out to be positive. Out
of these, only three isolates showed negative result for catalase test.
