Research Article: Effect of Nannochloropsis oculata and Isochrysis galbana on growth, water quality, biofloc, carcass fatty acids profile, and intestinal bacteria in Nile tilapia (Oreochromis niloticus) raised in zero-water exchange system

In this study, the effects of various algal resources on water quality, growth performance, body fatty acid composition, and intestinal bacteria of Nile tilapia were studied under a zero-water exchange biofloc system. Oreochromis niloticus with an initial mean weight of ۲.۷۳±۰.۲۷ g, was cultured in five experimental tanks (۱۵۰ L) including the control group (T۱), biofloc group (T۲), biofloc+ N. oculata group (T۳), biofloc+ I. galbana group (T۴), and biofloc+algal (T۵) for ۶۰ days. A total number of ۲۲۵ O. niloticus was used for this study (۱۵ individuals in each replication). The results showed the highest total ammonia nitrogen (۴.۵۴±۰.۰۵ mg L-۱) in the biofloc treatment (p<۰.۰۵). There were significant differences in the growth performance among the control group with other treatments (p<۰.۰۵). In terms of fillet quality, the highest amount of saturated fatty acids (۳۹.۷۹±۰.۲۵%) was found in the biofloc group. The highest monounsaturated fatty acids (۴۱.۸۷±۰.۹۹) and polyunsaturated fatty acids (۳۳.۲۵±۰.۹۳%) were obtained in the biofloc+algal treatment (p<۰.۰۵). All intestinal bacteria in the biofloc group were higher than the control group (P<۰.۰۵). The current study demonstrated that biofloc could promote the growth performance of unsaturated fatty acids in the fish fillet.

کلیدواژه ها:

Bacterial ، Nitrogen compounds ، Microalgae ، Carcass quality ، Biofloc technology