Increasing stocking densities affect hemato-immunological parameters of Nile tilapia reared in an integrated system with Pacific white shrimp using biofloc technology

The aim of this study was to investigate the effect on fish health indicators of different Nile tilapia (Oreochromis niloticus) stocking densities when reared in an integrated culture with Pacific white shrimp (Litopenaeus vannamei) using biofloc technology for 57 days. Three fish densities were evaluated: 8, 16 and 24 fish tank−1 with four replicates each. The experimental units comprised 800 L (useful volume) tanks for shrimp rearing and 90 L (useful volume) tanks for the culture of tilapia, which had an initial mean weight of 9.64 ± 0.14 g. A submerged pump located inside the shrimp tanks recirculated the water between the two units. The system was managed as a biofloc technology unit, with the addition of organic carbon to control ammonia and the monitoring of water quality, which remained within suitable ranges for both species. On day 57, fish were sampled for the assessment of the hemato-immunological variables. Fish reared under the highest stocking density exhibited significantly higher values of hematocrit and total leukocytes when compared to the two lowest densities (p