An investigation was conducted to evaluate the effect of dietary different levels of (0, 2.5, 5 and 10 g/kg) marjoram leaves supplementation for common carp (Cyprinus carpio) fries. 420 fries (averaged 0.34±0.1 g) were randomly distributed into four treatments, three replicates in 12 aquaria and fed experimental diets four times per day. Results revealed that marjoram leaves as feed additives in the diets for common carp fries did affect the growth performance parameters with significant differences (P<0.05) among all dietary treatments. A decreasing trend was observed when the inclusion of marjoram leaves in the diets increased. Fish fed M₁ (2.5 g/kg) diet showed the best FCR and significantly differed (P<0.05) among all dietary treatments. No significant differences were observed in the survival of fish fed the examined diets and fish fed M₃ diet gained the highest value (96.2%). Also, significant differences (P<0.05) were observed in the protein content of fish body and fish fed M₃ diet gained the highest value. Also, the lipid content was similar among all treatments. However, the inclusion of marjoram leaves in the experimental diets did not significantly (P>0.05) affect the condition factor (K), gonadosomatic (GSI), and hepatosomatic (HSI). Moreover, significant differences (P<0.05) were observed in viscerasomatic (VSI) indices values among all treatments. No diet-related histopathological changes were noted in all examined tissues such as liver, intestine and gonads of common carp fries.  The normality of all examined fish tissues indicated that marjoram leaves are safe to use in fish diets and can be added at 2.5 g/kg diet to improve the performance and feed utilization in the diets for common carp fries without any adverse effects.