A 60‐day feeding trial was conducted to evaluate the effects of feeding Houttuynia cordata leaf meal and extract on the growth performance, nutrient utilization and expression of insulin‐like growth factor‐I (IGF‐I) in Labeo rohita fingerlings. Two hundred seventy fingerlings were randomly distributed in six experimental groups in triplicates. Six isonitrogenous (350 g/kg CP) and isocaloric (17 MJ/kg DE) diets were prepared with graded levels of leaf meal (LM) and leaf extract (LE), namely C (control, without LE and LM), LE‐0.25 (2.5 g/kg LE), LE‐0.5 (5 g/kg LE), LE‐1.0 (10 g/kg LE), LM‐1.0 (10 g/kg LM) and LM‐2.0 (20 g/kg LM). Significantly (p < 0.05) higher IGF‐I expression, weight gain %, specific growth rate and lower feed conversion ratio were observed in LM‐1.0 followed by LE‐1.0 group compared to control group. Higher protease activity was observed in LE‐1.0 compared to other experimental groups, while no significant changes were found for amylase and lipase activities. Compared to control, muscle alanine aminotransferase and aspartate aminotransferase activities were significantly higher in treatment groups except for LM‐2.0. These results suggest that either LE‐1.0 or LM‐1.0 can be supplemented in the diet to improve the growth of L. rohita. However, the supplementation of 10 g H. cordata leaf meal/kg feed can be the better option considering the cost of extraction.

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Intensified aquaculture is highly susceptible to stress and diseases that leading to decreased production. But, intensification of culture is necessary to meet the world's increasing protein demand as capture fisheries fail to do so in future. Therefore, there are challenges to make the intensified aquaculture sustainable. However, several attempts have been made to mitigate the stress and disease outbreak in intensified aquaculture system (Sakai, 1999; Chinabut & Puttinawarat 2005; Jadhav et al., 2006). Once, antibiotics were deliberated as an onetime cure to all disease problems in aquaculture. But, use of antibiotics is no more a sustainable option to avoid bacterial infections or be used as growth promoter as it leads to development of the antibiotic resistant bacteria along with its residues in the environment and fish