Total lipids were extracted from biofloc sample according to Folch et al. (1957). Fatty acid methyl esters were prepared based on the procedure given in AOAC (1995). Briefly, the lipid extract was boiled in a condenser with 2 mL methanolic NaOH for first 5 min followed by 2mL BF3-methanol for the next 2 min. To recover the fatty acid methyl ester (FAME) in organic phase, 5 mL heptane was added and heated for 8 min, and washed with saturated NaCl solution into a separating funnel. The upper FAME layer was stored in glass vials at 0 °C for further analysis in GC–MS.