Evaluation of two types of bioflocs derived from biological treatment of fish effluent as feed ingredients for Pacific white shrimp, Litopenaeus vannamei

Abstract

Under laboratory-scale conditions, two types of bioflocs were used as a feed ingredient for Pacific white shrimp ( Litopenaeus vannamei). This feeding trial was conducted indoors in recirculating aquaculture systems with seawater renewal. Bioflocs were produced in sequencing batch reactors (SBR) using carbon supplementation (sucrose) and in a membrane biological reactor (MBR) without carbon supplementation. Both types of bioflocs were produced using tilapia farm effluent as a feed for the SBR and MBR systems. The bioflocs were dried and were used in shrimp feed as a replacement for fishmeal and/or soybean protein. A control diet (without bioflocs) was compared against four diets with MBR bioflocs (at 10, 15, 21, and 30% inclusion levels) and SBR bioflocs (at 10, 15, and 21% inclusion levels). At these biofloc inclusion rates, soy protein was replaced completely and fishmeal by as much as 67%. The control and biofloc diets were formulated to be equivalent for levels of crude protein, total fat, crude fiber, calcium, magnesium, phosphorus, potassium, and sodium. Seven juvenile shrimp were stocked per tank and each dietary treatment was tested using 8 replicates over a 35 day feeding trial. Dietary treatments had some impact on shrimp performance. Even though no differences ( P > 0.05) were observed between means for final survival (92.9 to 100%) or harvest biomass (536 to 574 g/m 2), some evidence ( P < 0.05) of faster growth rates was observed for diets with bioflocs inclusion compared to the control diet. Growth rates ranged from 1.44 to 1.66 g/week. Therefore, data indicate that bioflocs produced using either SBR or MBR systems could replace fishmeal and soybean protein. Furthermore, the SBR and MBR systems can be used to treat effluent from a tilapia farm thus reducing effluent waste into the environment.