This study aimed to assess the efficacy of BioPlus 2B, a probiotic containing Bacillus licheniformis and B. subtilis and Ferroin solution on growth performance, body composition and haematological parameters in kutum, Rutilus frisii kutum, fry. The fish were fed dry pellets containing various ratios of probiotics and Ferroin for 60 days after absorption of the yolk sac. At the end of the trial, growth indices (final weight, weight gain, specific growth rate, daily growth rate, food conversion ratio and condition factor), body composition (crude protein, crude lipid, ash and moisture) and haematological parameters [haematocrit (Hct), haemoglobin (Hb), red blood cells (RBC), white blood cells (WBC), neutrophils (NEUTR), lymphocytes (LYM), mean cell volume (MCV), mean cell haemoglobin (MCH) and mean cell haemoglobin concentration (MCHC)] were assessed. Regarding body composition, total protein levels were higher, and ash, moisture and lipid levels were lower in fish receiving the probiotic and Ferroin treatments compared with the control group (P < 0.05). Fish receiving diets supplemented with probiotics and Ferroin solution showed significantly better growth than those fed the basal diet (control). RBC, Hct, Hb, MCV, MCH and LYM were all highest in fish fed probiotic (1.6 × 10(9) CFU/g dry pellet) + Ferroin solution (7 mg/kg dry pellet) + dry pellets. These results indicate that the combination of probiotic and Ferroin solution represents an effective dietary supplement for improving carcass quality, growth performance and haematological parameters in kutum fry.