A Laboratory Study to Assess Separate and In-combination Effects of Zinc,Chromium and Nickel to the Fish Mystus vittatus

The present investigation is designed to work out the isolated and in-combination effects of Zn²⁺, Cr⁶⁺ and Ni²⁺ to a fish Mystus vittatus. From all the 12 combinations, 6 are antagonistic and 6 are synergistic. The combination Cr/Ni is highly synergistic while combination (Cr + Ni)/Zn is highly antagonistic in nature. The possible mechanisms responsible for antagonistic and synergistic combinations have been discussed and indicated as the occupation of critical receptor sites by less toxic metal (antagonism) or intrinsic affinity of the individual metal for the critical site or relative concentration and distribution of the metals within the target organ site (synergism). The results drawn can be indicated in terms of the effective concentration required to reach a particular level for a particular biological end point and can be expressed as follows.