Turmeric residue (TR), which is obtained from the extraction process of curcuminoids, may remain biological active compounds. This study was conducted to examine the effects of the TR on hematological parameters, nutrient digestibility, and growth performance in hybrid catfish (Clarias gariepinus × Heterobranchus bidorsalis). Three experimental diets were formulated denoted as follows: BD (Basal diet), BTR1D (BD plus 1% TR powder), and BTR2D (BD plus 2% TR powder). Twelve juvenile hybrid catfish with an initial body weight of 180 g were allocated to each of the 6 concrete tanks (350-L holding capacity), resulting in two replicate tanks per dietary treatment. For 4 weeks, the fish were hand-fed the experimental diets to apparent satiation twice daily. The results showed that the final body weight and weight gain tended to increase in fish fed TR-supplemented diets, and significant differences were recorded in the BTR2D group as compared to the BD group (P < 0.05). In contrast, FCR values were decreased in fish fed BTR1D and BTR2D in comparison with those fed BD, and the FCR value of the BTR2D group was significantly lower than that of the BD group (P < 0.05). Hemoglobin concentration, white blood cell count and protein and lipid apparent digestibility coefficients were higher in fish fed TR-supplemented diets than those fed BD. These results indicated that dietary supplementation of the TR was beneficial to hematological parameters, nutrient digestibility, growth performance, and feed utilization in hybrid catfish. The positive effects of the BTR2D on fish performances in the present study suggest that supplementation of the TR at the ratio of 2% in the diet may be necessary for hybrid catfish practical culture.
