author(s)
Kouberi Nath and Sanjay Kumar Das

abstract
A 60 days indoor trial was conducted at ICAR-RC for north eastern hill region, Umiam in glass aquaria (30L) without soil base. The performance of three stocking density @ 2.0 nos/m², 4.0 nos/m², 6.0 nos/m² with BFT and non BFT has been investigated using sweet potato powder as carbohydrate source. The water quality and growth performance of common carp (Cyprinus carpio) was access at different stocking density in bioFLoC and non biobloc system. The feeding rate was maintained @ 2% of body weight. The results show a significant difference (p<0.05) in total suspended solids (TSS), and FLoC volume among the treatments. The TSS, FLoC volume and total heterotrophic bacterial count (THB) was higher in 6 nos/m2 in BFT system. The biological oxygen demand (BOD) load and Aeromonas count was found highest in non BFT system at 6 nos/m². The transparency and water exchange rate were lowest at 6 nos/m2 stocking density in BFT system. The total ammonical nitrogen and phosphorus load also differs significantly in BFT and non BFT system at different stocking density. The survival was observed highest for 2 nos/m² in BFT system and lowest in 6 nos/m² in non BFT system. The daily growth rate (DWG) was not differing statistically among the treatments. The present study suggests that adding sweet potato as carbohydrate can increase the carrying capacity of culture system. Addition of sweet potato also reduce water demand by 20% at high stocking density culture.