The Study of Salinity and Formalin Stress Tests in Postlarval Feeding of Indian White Shrimp by Enriched Rotifers with Unsaturated Fatty Acids ( DHA , EPA ) and Vitamin C

Stress tests are commonly applied in shrimp hatcheries to estimate the quality of postlarvae to be used during growout. The highest larval survival rate during culture and in shrimp stress tests has been reported when specimens are offered a diet containing high levels of highly unsaturated fatty acids ( HUFA ) . Also vitamin C has positive effect to resistance and survival of larvae . In this study in postlarvae stage 1 in the salinity stress tests (10 and 20 ppt ) the highest survival rate was observed in treatment 3 ( 56.667 % and 90.00 % ) which was enriched with highly unsaturated fatty acids and vitamin C . As for the second, treatment 2 ( 43.333 % and 76.667 % ) which was solely enriched with highly unsaturated fatty acids showed significant differences at a level of ( P < 0.05 ) with treatment 3 . The difference between these two treatments and treatment 1( larvae fed rotifers cultured on Chlorella sp. ) and control ( larvae fed newly hatched Artemia nauplii ) was also significant . No significant difference was observed in formalin stress test ( 100 ppm ) in this stage between treatments 3 ( 86.667 % ) and 2 ( 80.00 % ) which shows the highest survival rate . But difference between them with treatment 1( 60.00 % ) which was unenriched and control ( 53.333 % ) was significant . Also, in postlarvae stage 5 in the salinity stress tests (10and20 ppt) the highest survival rate was observed in treatment 3 ( 56.667 % and 83.333 % ) and later treatment 2 ( 40.00 % and 70.00 % ) which showed significant difference . In this stage , the survival rate the treatment control ( 60.00 % and 86.667 % ) and treatment 3 showed no significant difference but they showed significant differences with treatment 1 and 2 .The lowest survival rate was observed in treatment 1( 26.667 % and 56.667 % ) . And the highest survival rate was observed in formalin stress test ( 100 ppm ) in this stage in treatments control , 3 and 2 ( 76.667 % , 73.333 % and 70.00 % ) among which there were no significant differences . However, the difference between these three treatments with treatment 1 ( 53.333 % ) was significant .