This study aims to evaluate the effects of different probiotic products on growth and survival rates of cobia (Rachycentron canadum) larvae. The experiment was conducted with completely randomized design comprising four treatments: (i) Coded probiotic A. (ii) probiotic B, and (iii) probiotic C and (iv) the control (no probiotic product application). Each treatment was triplicated. The 500-L composite tanks were used for the experiment Rearing water has salinity at 30 ppt and is continuous aerated. Cobia larvae with initial body length of 3.3 mm were stocked at 10 fish/litter. Algae Nanochloropsis were daily supplied to all treatments at density of 100,000 - 200,000 cells/mL During 3rt-10th days after stocking, fish was fed with Rotifer at density of 5-10 inds/mL, there times per day (6h00, 12h00 and 18h00). Artemia nauplius was supplied during the 7th - 10th day at amount of 0.5 - 1 Artemia/mL/feeding time, twice a day (9h00 va 15h00). From the 11th day to 21st day, all of treatments were fed with DHA Selco - enriched Artemia at density of 1 - 2 Artemia/mL/feeding times, twice a day (6h00 va 18h00). There was no water exchange dUring the experimental period of 21 days. Results showed that during the experiment, water quality parameters such as temperature, pH, NO2, NO3., TAN in the treatments applying probiotic products was more stable than the control treatment
however, all of parameters were in the suitable range for the normal development of fish. Mer 21 days of rearing, fry length varied from 20.96 to 22.18 mm, the growth rate was 0.88 - 1.03 mm/day (8.93 - 9.62 percent/day) and there was no statically significant difference among treatments (p0.05). Survival rates of fish in all treatments were in range of 6.91 - 9.65 percent. The highest survival rate was found in the treatment applying probiotic B (9.65 percent) which is significantly higher than those in the treatment applying product C and the control, but was not significantly different to those in the treamtment apllying product A (7.75 percent). Results showed that applying probiotics A and B during rearing improved the survival rates of cobia fry.