Abstract: Present study was carried out to assess the influence of three medicinal plants, Ocimum bascilicum, Adathoda vasica and Calendula officinalis on the biochemical parameters of normal and Aeromonas hydrophila-infected fish-labeo rohita. Fish of length, 5-9 cm were selected for the experiment. Five sets each of healthy live specimens and A. hydrophila-infected fish were kept in parallel pairs and each pair of fish sets were fed ad libitum for 15 days on one of the following compounded feeds: namely, normal fish feed (control groups), feeds supplemented at 3% concentrations with extracts of three plants. At the culmination of feeding experiment, biochemical analysis of serum for enzymes Serum Glutamate Oxaloacetate transferase (SGOT), Serum Glutamate Phospho Transferase (SGPT), Alkaline phosphatase, triglycerides, total sugars, serum protein were carried out from each set. Highest level of SGOT, SGPT, ACP was recorded in Ocimum basilicum supplemented group (60.0, 54.1, 26.3 mg dL-1). When infected maximum level was also observed in Ocimum basilicum supplemented group for SGOT, ACP (22.3, 19.3 mg dL-1) and for SGPT in Calendula officinalis supplemented group (17.5 mg dL-1). Lipid profile show contrasting result with maximum value recorded in infected animals, triglyceride and cholesterol showed maximum value in Calendula officinalis supplemented group (88.2, 96.4 mg dL-1) and for total sugar Ocimum basilicum supplemented group recorded maximum (96.3 mg dL-1). Highest serum protein content was in Calendula officinalis supplemented group (6.0 mg dL-1) and in infected animals in control with 3.2 mg dL-1. This study revealed that feed supplementation of three medicinal plant extracts alters biochemical parameters to overcome disease induced stress in fishes.