Introduction: This study aimed to determine the effect of different levels of ethanolic extract of Stachys lavandulifolia Vahl on the growth and nutritional indexes of (Cyprinus carpio) juveniles.
Materials & Methods: The fish (30.36±1.12 g) in 4 treatments fed for 45 days; control (without extract), and 3 groups were fed with different levels of extract (4, 8, and 16 mg/kg-1). In start, 10 every day at the end of the experimental period, biometric tests were done. Growth factors (final weight, total length, weight gain, weight gain percentage, daily growth rate, specific growth rate, feed conversion ratio and feed efficiency percentage) were calculated.
Results: The results showed that the growth factors in treatments fed with ethanolic extract of Stachys lavandulifolia were significantly increased in comparison to control (P<0.05). Among the growth indicators the highest growth performance was observed in fish fed by 16 mg/kg-1 of Stachys lavandulifolia extract (P<0.05). Due to the chemical compounds of Stachys lavandulifolia Vahl extract in improves growth, it acts as a natural antioxidant. The feed conversion ratio showed the lowest performance in the treatment containing 16 mg/kg-1 compared to the control and the percentage of feed efficiency showed the highest performance in the treatment containing 16 mg/kg-1 than the control.
Conclusion: According to the results, the addition of 16 mg/kg-1 of Stachys lavandulifolia extract to the Common carp diet has a significant effect on the growth indexes of this fish.