Effects of metals mixture on the growth and their bio-accumulation in juvenile major carps

Effects of waterborne and dietary metal mixtures (MMs) of copper (Cu), cadmium (Cd), zinc (Zn), nickel (Ni) and cobalt (Co) on the growth and their accumulation in fish, Catla catla, Labeo rohita and Cirrhina mrigala were examined under controlled laboratory conditions for 12 weeks. The exposure of MM, either waterborne or dietary, showed significant impacts on the growth of all the three fish species to exhibit significantly variable responses toward feed intakes, weight and length increments, and FCE. Dietary treatments caused significantly better feed intake and FCE than the fish exposed to waterborne treatments. Fish were found significantly more susceptible to waterborne than dietary MM treatments. Exposure of both waterborne and dietary MMs caused significantly variable accumulation of all metals in the fish body that followed: Zn greater than Ni greater than Cu=Cd greater than Co. Among the three fish species, C. mrigala showed significantly higher amassing of metals (21.79 plus minus 9.74 mug g-1), followed by that in C. catla (18.26 mug g-1) and L. rohita (17.33 mug g-1). Dietary intake of MM caused significantly higher accumulation of all metals than that of waterborne treatments. Accumulation of metals in fish body followed the order: liver greater than kidney greater than gills greater than skin greater than muscle greater than fins greater than bones. Both waterborne and dietary MMs caused significant toxicity to the fish in a synergistic/antagonistic way. Significant interactions among Cu, Cd, Zn, Ni and Co, in a mixture form, predict their competitive uptake that fluctuated significantly between waterborne and dietary treatments to cause significant distribution in various organs of three fish species.