Co-culture of whiteleg shrimp (Litopenaeus vannamei) and red seaweed (Gracilaria tenuistipitata) following biofloc technology with partially reduced feed ration

Abstract

A 60-day feeding trial was conducted to determine the suitable reduction in feeding rate of whiteleg shrimp (Litopenaeus vannamei), co-cultured with red seaweed, (Gracilaria tenuistipitata), in a biofloc system. In a 2 factors experiment (culture systems x feeding rates), shrimp and red seaweed were co cultured with and without biofloc at three different feeding rates (100%, 75%, and 50%). Each treatment was repeated three times and randomly designed in the 18 plastic tanks of 150 L at a salinity of 15 ppt. Red seaweed was added to each rearing tank at a rate of 1.5 kg/m3 , and molasses was used as a carbon source to maintain a C:N ratio of 15:1. Shrimp juveniles (0.47 ± 0.08 g) were stocked at a density of 300 shrimp/m3 with restrict water exchange throughout the experimental period. Results showed that shrimp had average final weights of 8.75-11.03 g, equivalent to specific growth rates of 5.51-5.90%/day, productions of 2.082.20 kg/m3 , and a feed conversion ratio (FCR) of 0.74- 1.24. The growth rate of shrimp in the biofloc treatment that received a 50% feed ration did not significantly differ (p> 0.05) from the 75% and 100% feeding treatments, and FCR was the lowest ompared to other treatments. Moreover, water quality in terms of TAN and NO2 - contents was maintained in a suitable range during shrimp culture. These findings revealed that co-cultured red seaweed and whiteleg shrimp in a biofloc system could lower feeding rates by 50%, equivalent to a 40.38% decrease in FCR, without ompromising the growth, survival, and production of shrimp.