A step toward a biofloc system with no-carbon addition: Increasing dietary lipid level enhances the water quality and body chemical composition without affecting tilapia health status

A 70-day experiment was carried out to evaluate biofloc system operation with no carbon addition by manipulating dietary protein and lipid levels for Nile tilapia (Oreochromis niloticus) cultivation. Three treatments were conducted; Control treatment (C; fed on a 30% crude protein [CP] diet supplemented with 3% vegetable oil [VO] + addition of external carbon source [ECS] in rearing tank), low protein-low lipid treatment (LPLL; fed on 23% CP diet supplemented with 3% (VO) + no addition of ECS) and low protein-high lipid treatment (LPHL; fed on 23% CP diet supplemented with 9% VO + no addition of ECS). The C treatment recorded the highest values (p < 0.05) in terms of final body weight (FBW), specific growth rate, floc volume, total suspended solids, and ammonia nitrogen. No significant differences were observed between C and LPHL treatments regarding FBW and protein efficiency ratio. The liver sections of LPHL treatment showed better values for histological alteration index compared to the control. It could be concluded that applying a biofloc system with no carbon addition using LPHL diets may afford better water quality conditions, limit the environmental impact and decrease dietary costs with limited effect on fish performance.

Automated summary

A 70-day experiment was conducted to evaluate the operation of a biofloc system with no carbon addition in Nile tilapia cultivation. The results showed that using a low protein-high lipid diet without carbon addition can improve water quality, reduce environmental impact, decrease dietary costs, with limited effect on fish performance.