The use of biofilm and different feeding rates in biofloc culture system: the effects in shrimp growth parameters

This study evaluated the use of biofilm in a Litopenaeus vannamei biofloc system using different feeding rates. Shrimp juveniles (0.89 ± 0.35 g) were stocked at 300 shrimp m⁻³ in 24,150-L tanks. The feeding rates were calculated by considering an expected weekly growth of 1 g week⁻¹ and an estimated weekly mortality of 0.5%. Each treatment corresponded to a different feeding rate, and each feeding rate corresponded to a fixed food conversion ratio. Thus, the treatments tested were as follows: T0 and T0+B (without addition of artificial food, with and without biofilm addition, respectively); T0.6 and T0.6+B; T1.2 and T1.2+B; and T1.8 and T1.8+B. The study lasted 42 days. At the end of the study, shrimp that were grown with no artificial food presented lower final weights and minor survival, independent of the addition of biofilm. The T1.2+B treatment did not differ significantly from the T1.2, T1.8, and T1.8+B treatments for the growth and feeding parameters. The survivals were higher than 91% in all of the feed treatments, and no significant differences were detected among these treatments. In contrast, the results allowed the conclusion that the presence of biofilm in the T1.2+B treatment represented a feed saving of 35% of the total amount of artificial food offered. This could represent a significant value in the cost of operation and may make the biofloc technology (BFT) system more cost-effective and environmentally friendly. The use of BFT in conjunction with biofilm can benefit shrimp farming by reducing the amount of feed supplied.