Effects of some trace heavy metals on Poecilia reticulata (Peters).

Three trace heavy metals viz., nickel, copper and zinc were studied for the ir toxic action against Poecilia reliculata (Peters). Among these, copper w as found to be most active followed by zinc and nickel. Accumulations of th ese metals as well as behavioural studies were carried out after exposing f ish to sub-lethal concentration of LC20 It was found that the highest quant ity of nickel was accumulated in the fish body followed by zinc and copper. After exposure to sub-lethal concentration of metals some behavioural chan ges in fish were observed due to stress, such as mucus like secretion over gills, excessive excretion, anoretic condition and increased distance betwe en gills and operculum. In all the cases increased fin movement: was observ ed. Role and use of such changes as biological indicators or as biological early warning system in water quality assessment has been discussed.