β1,3 glucan extracted from the cell wall of a marine yeast Candida sake S165 was tested for its potential as an immunostimulant in Fenneropenaeus indicus postlarvae through dip treatment. Glucan suspensions of different concentrations viz., 0.1 mg/ml, 0.5mg/ml, 1mg/ml and 2mg/ml were prepared and postlarvae were subjected to dip treatment for 3 hours. Postlarvae dipped in solution without glucan addition was considered as control. To find out the extent and duration of protection conferred by glucan dip treatment White Spot Syndrome Virus (WSSV) challenge was conducted on 10th, 15th and 20th day
of postdip treatment. Post-challenge survival showed that 0.5 mg/ml and 1 mg/ml glucan concentration impart better protection whereas, higher concentration, 2mg/ml gave adverse effect on post-challenge
survival. Challenge on the 20th day post-glucan treatment resulted in considerable mortality in all the four treatment groups. The study showed that the protection from WSSV through β1,3 glucan is short lived and lasted for a period of only 10 to 15 days.

Fenneropenaeus indicus,glucan, dip treatment, immunostimulant, short-term protection