Integrated recirculating aquaculture system for mullet and shrimp using biofloc technology

Abstract

We evaluated an integrated system for rearing Pacific white shrimp (Litopenaeus vannamei) and white mullet (Mugil curema) in an experimental-scale biofloc system. Performance of the animals, water quality, phosphorus and nitrogen retention and mass balance, and fish hematology and immunology were compared among two treatments: 1) shrimp with mullet integrated system (Shrimp + Mullet), and ii) shrimp without mullet system (Shrimp). A tank with 800 L of useful volume was used to rear the shrimp with a density of 250 shrimp m−3. Another tank with 90 L of useful volume was maintained for rearing fish (15 mullet tank−1) in the Shrimp + Mullet treatment. The shrimp treatment also used the 90-L tanks, but without the fish. Water was recirculated into the mullet tanks via a submerged pump and returned by gravity to the shrimp tanks. The shrimp were fed four times a day. A feeding table was used to adjust the amount of feed provided, and the fish were fed only once daily with a ratio of 1% initial biomass to stimulate biofloc consumption (BFT). After 53 days, shrimp growth (final weight 12.56 ± 0.22 g) and survival (91.8% ± 2.9%) were similar between treatments. Fish had adequate survival (91.1% ± 10.2%), and adequate growth for Mugil species (0.71 ± 0.05 g week−1) in the integrated system. In the Shrimp + Mullet treatment, animal productivity was increased by 11.9% by combining Shrimp + Mullet biomass, when compared to the Shrimp treatment. The Shrimp + Mullet treatment also demonstrated a 16.8% increase in phosphorus retention compared to the Shrimp treatment. The hemato-immunological parameters showed that fish kept in a biofloc system had adequate values comparable to those reported for Mugil species. Thus, these experimental-scale results demonstrate that the integration of shrimp and mullet in biofloc systems increases yield and phosphorous retention without compromising fish health and shrimp growth. In addition, we recommend reproducing this integrated system over a longer period and at commercial-scale, supporting an economic analysis.