The infected larvae appear luminescent in darkness and suffer heavy mortality.  

CAUSE  

Luminescent bacteria such as Vibrio harveyi.  

DIAGNOSIS  

Based on gross signs and symptoms and microscopically demonstrating swarming bacteria within the haemocoel of moribund prawn larvae. The luminiscent bacteria can be isolated on Zobell's marine agar or a selective medium for luminous bacteria and identified based on their morphological and biochemical characteristics.  

PREVENTION  

Use chlorinated (calcium hydrochlorite 200 ppm for 1 hour) and ultraviolet irradicated water. Clean bottom debris in rearing tanks daily.  

CONTROL  

Exchange water upto 80%daily with sand filltered /UV sterlizes seawater.