Inclusion of biofloc meal as a mineral source in diets for Peneus vannamei cultured in oligohaline water

Biofloc meal (BM) obtained from whiteleg shrimp culture waste is a nutritious ingredient commonly used for its high protein content. Nevertheless, its elevated ash value could be of interest in oligohaline culture, where dissolved ions in water are limited. Five isonitrogenous and isolipidic experimental diets were formulated, consisting of a control diet (BM0, no biofloc meal inclusion) and four other diets (BM2.5, BM5, BM10, and BM20) with increasing BM concentration in each diet, all tested in triplicate. Juveniles from Peneus vannamei (0.40 g) were cultured at a density of 150 shrimps.m⁻³ in oligohaline water (1.22 PSU), for 60 days in a chemoautotrophic biofloc technology (BFT) system. The growth parameters and ionic concentration/ratios were monitored during the experimental period. The results demonstrated significantly higher survival (84.6 %) in the BM20 group and lower survival in the BM0 group (40 %). For all treatments, nitrate (NO₃^--N) reached toxic levels, which may explain the observed mortality. In addition, an increase in water salinity was observed, resulting in a significant accumulation of Sodium (Na⁺) in the treatment BM20. In conclusion, BM conferred protection in whiteleg shrimp against nitrate when cultured in low salinity, resulting in better survival and overall productive parameters for P. vannamei.