Nile tilapia production in polyculture with freshwater shrimp using an aquaponic system and biofloc technology

Abstract

This study aimed to evaluate the performance of Nile tilapia, freshwater shrimp, lettuce, and watercress in an aquaponic system used in conjunction with biofloc technology. Experimental units consisted of an aquaponic module comprising two containers, one to accommodate vegetables (500 L media-filled bed with gravel) and the other to stock fish and shrimps (1000 L rearing tank). The experiment was carried out in a randomized complete block design with two treatments [an aquaponic system with clear water (ASCW) and an aquaponic system with biofloc technology (ASBFT)] and two blocks (periods). Each treatment had three replicates within each block, totaling six experimental units per block. The final weights of Nile tilapia (ASCW = 546.0 g; ASBFT: 565.0 g), freshwater shrimp (ASCW = 18.82 g; ASBFT: 18.44 g), and vegetable biomass (ASCW: 1.10 kg/m2 of lettuce and 1.57 kg/m2 of watercress; ASBFT: 0.94 kg/m2 of lettuce and 1.98 kg/m2 of watercress) did not differ significantly between the two treatments. Similarly, there were no significant differences between treatments with respect to other zootechnical performance variables of the evaluated organisms. There was, however, a greater (P < 0.05) accumulation of fat in the fillets of Nile tilapia reared in the ASBFT system (0.97%) than in those of fish reared in the ASCW system (0.76%), as well as a lower oscillation of nitrite levels. Therefore, the use of biofloc technology in conjunction with aquaponics facilitated the maintenance of zootechnical performance and contributed to an increase in the fat content of Nile tilapia fillets and better control of nitrite production.