Abstract: Background and Objective: Several industries release their waste water directly in to the aquatic ecosystems without appropriate treatment. The toxic heavy metals present in that waste water cause water pollution and also affect the aquatic organisms. Hence, the present work has been aimed to find out the acute toxicity of nickel, chromium and their combinations to the fingerlings of the Indian major carp, Cirrhinus mrigala. Materials and Methods: The fingerlings of C. mrigala were subjected to static bioassays to determine the acute toxicity of chromium, nickel and their combinations. Using probit analysis, 24, 48, 72 and 96 h LC50 values were determined along with 95% fiducial limits. The results were subjected to Chi-square test to find out the goodness of fit. Results: The 96 h LC50 values of chromium, nickel, Ni+Cr and Cr+Ni were 21.3, 25.8, 42.4 and 76.0 ppm, respectively. Chromium was more toxic to the fish than nickel. When all the tests are compared, Cr+Ni combination was the most toxic to the fish. Conclusion: Among the metals tested chromium were more toxic to the fish than that of nickel.