This study examined the effects of a commercial Lactobacillus probiotic on growth, survival and resistance of western white shrimp (Litopenaeus vannamei) larvae against salinity and formalin stresses in the Persian Gulf and Oman Sea Ecology Research Center. In this experiment, larvae were fed 6 times a day from mysis I (M1) step to post larvae 5 over 3 treatments including a control treatment C (without probiotic) and 2 experimental treatments namely A (having probiotic enriched rotifer) and B (having probiotic enriched rotifer and adding probiotic powder directly to the water). Larvae were stocked in 9 plastic tanks (20-liter) containing 10 L of seawater at a density of 50 larvae per liter. Three replicates were used for each treatment. At the end of the experimental period biometric larvae were studied under salinity and formalin stresses. Results showed that using probiotic bacteria had significant and positive effects on shrimp resistance, survival and growth (p<0.05) and that growth and survival rate of larvae fed with A and B treatments were significantly higher than that of the control group (p<0.05). The results of the stress tests also indicated that probiotic containing treatments (A and B) had significantly higher survival rates in salinity and formalin stresses than the control treatment (p<0.05). The highest survival rate and resistance were observed in treatment B which was not statistically different from that of treatment A (p>0.05). According to the results we may conclude that the use of probiotic powder is effective in increasing growth, survival and resistance rate of western white shrimp in the larval and post larval stages.

Keywords:Brachionus plicatilis, Probiotic, Resistance,Litopenaeus vannamei