Catalase activity in response to binary metal mixture of Zn + Ni was studiedin gills, hepatic, renal and cardiac tissues of Catla catla. A total of 30 fishfingerlings were kept in two glass aquaria (15 in controlled condition and 15in metal mixture containing aquarium) for the period of two weeks. Afterthe completion of the trial period, fish were dissected for different organcollection. The extracted organs were homogenized in phosphate buffer (50mM; pH 7.0). The activity of catalase was determined by absorption at 240nm by using the standard methods. The inferences showed higher catalaseactivity in liver (223.33 +-1 UmL-1), kidney (163.33 +- 0.7 UmL-1), gills (123.33+-0.9 UmL-1) and cardiac (120 +-3 UmL-1) tissues of Zn + Ni treated fish incomparison to controlled fish liver (116.66 +-2 UmL-1), kidney (101.66 +-1UmL-1), gills (96.66 +-0.66 UmL-1) and cardiac tissues (70 +-0.33 UmL-1) in thisstudy. Statistically, significant differences at p ? 0.05 was observed forcatalase activity between Zn + Ni stressed and control fish groups. While, indifferent organs of both group of fishes the catalase activity order wasobserved as hepatic > renal > gills > heart. Findings of this study would behelpful in monitoring aquatic ecosystems using fish antioxidant systemwhich acts as a bio-indicator of metal contamination.
Keywords: Heavy metals, Antioxidants, Major carp, Aquatic pollution,Biomarkers.