The present study evaluates the biofloc technology (BFT) in light-limited tank culture of Nile tilapia
(Oreochromis niloticus). Two biofloc treatments and one control were managed in 250 l indoor tanks: BFT fed
a diet of 35% crude protein (CP), BFT fed a diet of 24% CP, and clean water control without biofloc with 35% . Determination of biochemical composition of biofloc
Biofloc samples for biochemical analysis were collected on a
fortnightly basis. Concentrated floc samples collected from each tank
using a floc separator were dried in an oven at 102°C until constant
weight and then preserved in a refrigerator. At the end of the
experiment, tank-wise pooled samples were ground and processed for
proximate analysis followingAOAC (1990). For ash contents, a known
amount of dry sample was burnt in a muffle furnace at 550 °C for 4 h
and the ash cooled and weighed. The crude protein content was
determined by the Kjeldahl method. Lipid content was determined
with Soxhlet apparatus. The energy content was determined by a
bomb calorimeter (Gallenkamp Autobomb). The C:N ratios were
determined using a CHN analyzer (Perkin Elmer 2400 Series II). Biofloc
samples for fatty acid analysis were collected at the end of the
experiment and freeze-dried. Fatty acid analysis was undertaken by a
modified direct methylation method (Christie, 2003) using an N-Evap
112 Liquid Gas Chromatograph (Organomation Associates Inc.).