Mandarin orange peel (Citrus reticulata) contains nutrients that are beneficial for fish and has the potential as a feed additive. This study aimed to evaluate the effect of adding mandarin orange peel flour with different doses on hematological parameters, including the number of lactic acid bacteria in the intestine, growth performance, feed utilization and survival rate of the catfish (Pangasianodon hypophthalmus) seeds. This study consisted of four treatments and three replications, namely the dose of orange peel flour of 0, 2.5, 5.0, and 7.5g kg^-1 diet. A total of 180 catfish, measuring 9.08 ± 0.31g, 15 of them each were reared in plastic containers with a volume of 40L for 30 days and fed twice a day ad satiation according to treatment. The results showed that the addition of mandarin orange peel flour in the diet had an effect on hematological parameters, the number of lactic acid bacteria, growth performance and feed utilization of catfish (P<0.05). Several hematological parameters such as hemoglobin, leukocytes, monocytes and neutrophils were higher with the addition of orange peel flour in the diet compared to the control. The highest number of lactic acid bacteria, weight gain, length growth, and specific growth rate were shown by T1, 3.95 log CFU mL^-1, 6.69g, 12.57cm, 1.79% day^-1, respectively (P<0.05). The same thing was also shown in the efficiency of feed utilization and protein conversion ratio, 74.67% and 2.02%, respectively  (P<0.05), while the survival rate of all treatments were 100%. Based on these results, it can be concluded that mandarin orange peel flour with a dose of 2.5g kg^-1 diet is the best dose as a feed additive for the catfish seeds.