Levels of selected heavy metals in commercial fish from five freshwater lakes,Pakistan

The levels of As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn and Hg are estimated by atomic absorption in the muscle of six commercial species of fish belonging to five freshwater lakes of Pakistan. The species included Mastacembelus armatus, Tor putitura, Mystus seenghala, Wallago attu, Catla catla and Labeo rohita. The fish were procured in comparable weight ranges so that a viable comparison of trace metal content could be effected. As, Fe, Pb, Zn and Hg showed elevated levels of 0.006–6.967, 0.933–6.133, 0.060–4.108, 0.978–5.363 and 0.030–3.211 μg/g, wet weight. The relevant statistical parameters, such as standard deviation, standard error, skewness and its t‐value are also reported for establishing the randomness of the distribution in relation to the corresponding data of freshwater lakes of the world and examined in view of species‐specificity and origin.