Study on floc characteristics and bacterial count from biofloc‐based genetically improved farmed tilapia culture system

Abstract

The present study endeavoured to investigate the efficacy of biofloc technology (BFT) and clear water system (CWS) on nursery rearing of genetically improved farmed tilapia (GIFT). The study used outdoor lined pond (0.01 ha), in duplicate, to explore the bacterial community in culture water and gut flora of GIFT and floc characteristics of both systems. Each pond was stocked with 5,000 numbers (0.2 ± 0.02 g/fish) of GIFT fry and reared for 30 days. Biofloc, with carbon: nitrogen ratio of 10:1, was developed and maintained using distillery spent wash (DSW) as organic carbon source and provided with intensive aeration. Total heterotrophic bacteria (THB), Vibrio and Bacillus count of culture water and gut samples were significantly (p < .05) differed between BFT and CWS. Floc volume, size, settling velocity, porosity and floc volume index were documented from BFT system. Plankton count was significantly differed (p < .05) between the BFT and CWS. BFT showed pleiotropic beneficial effect on rearing medium and species health through colonization of probiotic heterotrophic bacteria and elimination of pathogenic bacteria in the gut. Novelty of floc characteristics measured in the present study would help to form the base clue for the scientific understanding of biofloc system which paves to promote the BFT as sustainable aquaculture practice.