Eeffect of different dietary carbon sources on water quality, growth performance and survival of
western white shrimp Litopenaeus vannamei post larvae was investigated in zero-water exchange
system. Shrimp postlarvae with mean weight of 98.47±8.60 mg and mean length of 22.39± 1.70
mm were fed for 32 days in fiberglass containers with 130 liters volume of water and density of 1
individual per liter in five treatments including one control with water exchange and four biofloc
treatments with adding different carbon sources including molass, starch, wheat flour and mixture
of them at equal weight ratios with 15% to 9% of body weight. In the values of water quality
parameters including temperature, salinity, dissolved oxygen and pH, no significant differences
were observed among the biofloc treatments (P>0.05). Maximum pH (8.27 ± 0.09) and maximum
dissolved oxygen (6.37 ± 0.56 mg/lit) was in water exchange treatment. Maximum and
minimum level of ammonia was 0.43± 0.34 and 0.09± 0.07 mg/lit in water exchange treatment
without floc and biofloc treatment with adding starch of carbon sources, respectively and showed
significant difference between treatments (P <0.05). The highest increase in body weight
(1640.43± 231.28 mg), growth rate (51.26± 7.23 mg per day), specific growth rate (8.97± 0.42
%/day) and biomass (190.29± 26.83mg) was observed in biofloc treatment with adding molass
and the highest survival rate (90± 0.77%) was obtained in biofloc treatment with adding mixture
of carbon sources. The highest feed conversion ratio (1.52±0.23) and the lowest feed efficiency
(66.81±7.95) were obtained in water exchange treatment without floc, showing significant
difference compared to the other treatments (P <0.05). The results showed that using biofloc
technology with zero- water exchange system and adding carbonaceous organic matter could help
to recycle waste and improve the water quality. Moreover, the presence of biofloc improved
growth performance, feed utilization and production of western white shrimp in zero water
ecxhange rearing system.