Journal of Fisheries and Aquatic Science1816-49271996-0751Academic Journals Inc.10.3923/jfas.2006.277.283BensonN.U. EtesinM.U. EssienJ.P. I.U. Umoren UmohM.A. 3200613Fishes are important bioindicators of the integrity of aquatic ecosystems and were used to evaluate the status of heavy metal pollution in an oil impacted aquatic ecosystem (Imo River) located within the Niger Delta region of Nigeria. The concentrations of Cd, Cr, Cu, Fe, Pb, Mg, Mn, Ni and Zn were determined using inductively coupled plasma spectrometer (Optima 3000-Perkin Elmer). The metal concentrations in liver and muscle tissues of Ethmalosa fimbriata (bonga fish), Chrysichthyes nigrodigitatus (catfish), Lutiana ava (pink snapper), Stellifer lancelatus (croaker) and Tilapia guineensis (Tilapia) were consistently higher in the livers than in the muscle tissues of all the five fishes. Magnesium concentration was anomalously higher in the muscle tissue than liver of C. nigrodigitatus, E. fimbriata and L. ava but not in S. lancelatus and T. guineensis. Muscle-liver ratios (MLRs) of the respective heavy metals ranged between 0.089 (CuM:CuL) and 1.299 (MgM:MgL) for C. nigrodigitatus, 0.186 (CrM:CrL) and 1.401 (MgM:MgL) for E. fimbriata, 0.194 (CuM:CuL) and 1.498 (MgM:MgL) for L. ava, 0.131 (CuM:CuL) and 0.646 (NiM:NiL) for S. lancelatus, 0.009 (CuM:CuL) and 0.916 (MgM:MgL) for T. guineensis. Interestingly, copper indicated least MLR in almost all the investigated fishes except in E. fimbriata. Magnesium showed the highest MLR in all fish species except in S. lancelatus. On the other hand, the cadmium/zinc ratios were higher in the muscle tissues than livers of all the fishes analyzed except in E. fimbriata. The threshold contamination value for human dietary risk was however, not exceeded.]]>Akueshi, E.U., E. Oriegie, N. Ocheakiti and S. Okunsebor,200368286Arellano, J.M., J.B. Ortiz, D.S. Capeta and M.L.G. Canales et al.,199915485488Beauvias, S.L., S.B. Jones, J.T. Parris, S.K. Brewer and E.E. Little,2001Oncorhynchus mykiss).]]>498490Castano, A., W. Carbonell, G. Carbalo, C. Fernandez, S. Boleas and J.V. Tarazona,1998Oncorhynchus mykiss).]]>412935Cervigon, F.,1993Vol. 2.pp: 497pp: 497Cicik, B. and K. Engin,2005Cyprinus carpio (L. 1758).]]>29113117Fausch, K.D., J. Lyons, J.R. Karr and P.L. Angermeier,19908123144Ho, K.C. and K.C.C. Hui,200126303308Hossain, M.S. and Y.S.A. Khan,200127165168King, R.P. and G.E. Jonathan,2003pp: 166pp: 166Koli, A.K. and R. Whitmore,19839125127Kucuksezgin, F., A. Kontas, O. Altay, E. Uluturhan and E. Darilmaz,2006324151Lawani, S.A. and J.A. Alawode,199684749Lemaire-Gony, S. and P. Lemaire,1992Anguilla anguilla.]]>22145160Matagi, S.V., D. Swai and R. Mugabe,199882335Mazon, A.F., C.C.C. Cerqueira and M.N. Fernandez,2002Prochilodus scrofa.]]>885263Mengel, K. and E.A. Kirkby, 19791st Edn.,Omeregie, E., M.O. Okoronkwo, A.C. Eziashi and A.I. Zoakah,2002175559Ryams-Keller, A., K.E. Olson, M. Mc Gaw, C. Oray, J.O. CarIson and B.J. Beaty,1998Aedes aegypti (Diptera: Culicidea) Larvae.]]>394147Scheyer, J.M.,20002000pp: 479484Soengas, J.L., M.J. Agra-Lago, B. Carballo, M.D. Anders and J.A. Veira,199657625631Sorensen, E.M.B.,1991Stiassny, M.L.,199621713Toham, A.K. and G.G. Teugels,19993972938Voight, R.H.,200352305318Whitefield, A.K.,199634557Widianarko, B., C.A.M. Van Gestel, R.A. Verweij and N.M. Van Straalen, 2000Poecilia reticulata (Peters), from urban streams of Semarang, Indonesia.]]>46101107Yilmaz, A.B.,2005Mugil cephalus L.) and Sea Bream (Sparus aurata L.) caught in Iskenderun Bay (Turkey).]]>29257262Zweig, R.D., J.D. Morton and M.M. Stewart,1999