Integrating clams and Dicentrarchus labrax in groundwater-based aquaculture: A prototype for bioremediation and enhanced fish performance, health and production

A 90-day growth trial evaluated seabass performance and welfare when integrated with carpet-shell Ruditapes decussatus (CSC) and short-necked Paphia undulata (SNC) clams in saline groundwater-based culture. Seabass (n = 270) weighing 90.92 ± 0.15 g/fish were stocked in nine 1000-L tanks (30 fish/tank), which were divided into three groups in triplicate: (SB) seabass, (SB-CSC) seabass with carpet shells, and (SB-SNC) seabass with short-necked clams. Two kgs of CSC and SNC (mean weights of 10.70 and 10.40 g/clam) were suspended in four floating trays (0.5 kg/tray) in the SB-CSC and SB-SNC water tanks, respectively. The daily feeding was 3 % of the fish weight, and the water exchange was 5 %. The results revealed that the SB-CSC and SB-SNC groups had healthier culture water (higher dissolved oxygen (DO 2 ) and lower levels of NH 3 , NO 2 , and heavy metals) than the SB group. Both the SB-CSC and SB-SNC groups presented reduced heavy metal levels in fish muscles but improved growth, feed efficiency, and crude protein. Furthermore, the integrated groups presented significant improvements in serum growth hormones, antioxidant and immune parameters and declines in metabolic (ALT, AST and urea) and stress (i.e., cortisol and glucose) markers. Therefore, coculturing seabass with SNC appears most beneficial and is recommended for saline groundwater-based aquaculture systems.