Mineral supplementation in biofloc influences growth and haemato-biochemical indices of Genetically Improved Farmed Tilapia reared in inland saline ground water

An experiment for a period of 60 days was performed with species specific mineral supplementation in biofloc system for GIFT tilapia reared in inland saline water. Four different concentrations of formulated mineral mixture (10, 15, 20, 25 g L-1) were supplemented in the subculture of biofloc inoculum for different treatments (T1, T2, T3, and T4). In contrast, two control groups (conventional culture system (C) and a standard biofloc control (BC) devoid of mineral supplements) were maintained. Major water quality parameters were optimal except alkalinity and pH, which were fluctuated in the treatment groups, and higher turbidity was noticed only in the T4 group. The minerals supplemented groups had lower levels of TAN, nitrite (NO2) and nitrate (NO3) than conventional biofloc system (BC). Floc parameters such as floc volume, total suspended solids (TSS), total dissolved solids (TDS) and total solids (TS) were higher than the control. Haematological parameters Hb (haemoglobin) and WBC (white blood corpuscles) of fish reared in treatments were higher, ranging from (8.2 +/- 0.64 -10.47 +/- 0.66 g dL(-1)) and (187.83-215.17 +/- 6.58 per cumm) respectively (P < 0.05) compared to both the controls. Serum parameters of fish was recorded to be higher in T2. The proximate composition analysis revealed an enhanced crude protein content (33.22 +/- 1.00%, 67.68 +/- 0.2%) and crude lipid (5.24 +/- 0.22% & 15.18 +/- 0.58%) (P > 0.05) content from BC, but ash content (39.11 +/- 0.1% & 20.35 +/- 0.21%) from T4 in both dried biofloc and fish samples were higher than rest of the groups. Specific growth rate (SGR) and weight gain (WG) were recorded to be significantly higher in the T2 group. Feed conversion ratio (FCR) was observed to be better in all the treatments and the BC group than conventional control. The current investigation showed that subculture of biofloc inoculum supplemented with formulated mineral mix of 15 g L-1 could be effective in terms of water quality maintenance, feed utilization, growth, survival and biochemical parameters of GIFT tilapia reared in inland saline ground water.