This study evaluated the effect of adding dry biomass of the microalgae Arthrospira platensis (Spirulina ) in to the water on shrimp growth, water quality and proximal composition of Penaeus vannamei post-larvae in a biofloc system. Four treatments were tested: (BFT) control without A. platensis; (Sp40 ) biofloc with 40 mg L−1 mg/L of A. platensis; (Sp50 ) biofloc with 50 mg L−1 of A. platensis; and (Sp60 ) biofloc with mg L−1 of A. platensis. The shrimp with an initial average weight of 0.015 ± 0.009 were stocked at a density of 2000 post-larvae m3 in polyethylene tanks with a useful volume of 50L and fed commercial feed. The experiment lasted 35 days and assessed zootechnical parameters, water quality and the proximal composition of the shrimp and the biofloc . Treatments with A. platensis showed improved biomass gain, better survival, and feed conversation rate, with a higher protein content in the shrimps when compared to control. The water quality parameters were significantly influenced by A. platensis , with reductions in pH and alkalinity in the treatments with the additions of Spirulina , particularly in Sp60 , which showed the lowest values. Nitrate and phosphate concentrations increased in all Spirulina treatments compared to the control, with the highest values observed in the Sp50 and Sp60 treatments. However, all water quality parameters remained within tolerance levels for shrimp growth. Thus, among the treatments tested, the treatment with addition of 50 mg L−1 of A. platensis powder positively influenced the survival and growth of the shrimp and improved their nutritional composition in the nursery phase of P. vannamei in the biofloc system.
Keywords: Spirulina; post-larvae; shrimp performance; proximal composition.