Water-Use Efficiency and Physiological Responses of Juvenile Northern River Shrimp (Cryphiops caementarius) Cultured in Biofloc Systems Using Molasses and Chancaca as Carbon Sources

Biofloc technology (BFT) is based on the reutilization of nitrogenous waste generated by cultured organisms through the biotransformation of these compounds primarily into microbial biomass, allowing a reduction in water exchange. The aim of this study was to evaluate BFT as a water-saving culture strategy, using two carbon sources (chancaca and molasses), and to assess its effects on water-use efficiency, growth performance, digestive enzyme activity, and physiological responses in juvenile northern river shrimp (<i>Cryphiops caementarius</i>). The experiment was conducted in triplicate using 400 L fiberglass tanks, with an initial stocking density of 75 shrimp m^-2 and an average individual weight of 0.85 ± 0.65 g, over a 157-day rearing period. Water quality parameters were maintained within suitable ranges throughout the study. Significant differences were observed in the composition of bacterial and plankton communities among the biofloc treatments, whereas no significant differences were detected in growth performance or digestive enzyme activities. Heat shock protein 70 (Hsp70), a stress-related biomarker indicative of physiological responses, exhibited higher levels in the biofloc treatment supplemented with molasses. Overall, BFT treatments reduced water exchange by 81.6% while maintaining comparable biological performance to the control, indicating that biofloc technology represents a water-efficient and environmentally sustainable culture approach for juvenile <i>Cryphiops caementarius</i>, an endemic freshwater shrimp species, particularly in water-limited regions of northern Chile.