Water quality and growth of juvenile specimens in giant freshwater prawn Macrobrachium rosenbergii (De Man, 1879) cultures applied in recirculation and biofloc systems

Abstract

Biofloc research commenced in the late 1970s, with the white shrimp Litopenaeus vannamei and the Nile tilapia Oreochromis niloticus the most commonly studied species. The present study evaluated M. rosenbergii cultures in recirculation and biofloc systems by comparing the water quality and productive performance of juveniles in both systems. The study was based on a simple randomized experimental design with a recirculation and biofloc treatment, each conducted in triplicate. The initial length and weight of the organisms was 1.04 cm and 0.31 g (recirculation) and 1 cm and 0.30 g (biofloc), respectively, while the bioassay, which lasted nine weeks, was undertaken in a salinity of 5 ppm with a natural photoperiod (12:12). The present study monitored basic variables corresponding to the water, survival, growth (in weight), and the composition of the plankton.The basic variables of the water (temperature, salinity, and pH) were kept within the recommended range for the culture. Of the plankton observed in the biofloc, nematodes, rotifers, cyanobacteria, ciliates, heliozoa, and dinoflagellates predominated. The organisms grown in the recirculation system reached 5.35 cm in length and 1.28 g in weight, while those grown in the biofloc reached 5.18 cm and 2 g, with significant differences in individual weight observed. Survival in the recirculation and biofloc systems was 73% and 60%, respectively, with significant differences observed. It is concluded that, although the survival rate was higher in the recirculation system, the weight of individual organisms was higher in the biofloc treatment.