George Ubong Uwem, Asuquo Francis Emile, Idung Joseph Udo and Andem Andem Bassey
Three freshwater fishes (Tilapia zilli, Oreochomis niloticus and Schilbe mystus were caught from Cross River system between the period of February to April, 2012. The bone, liver and gills from the three species were carefully dissected for the determination of heavy metals. Levels of heavy metals were determined using Perkin-Elmer Analyst 300 Atomic Absorption spectrophotometer (AAS). The maximum concentration of heavy metals studied was observed in the liver tissues, while bone tissues had the least concentration. The highest concentration of copper was observed in O. niloticus, while Schilbe mystus show the least. For cobalt concentration, the maximum was obtained in Schilbe mystus and the minimum in T. zilli and O. niloticus. High levels of Lead (Pb), Iron (Fe), and Cobalt (Co) were found in the liver tissues of T. zilli and O. niloticus, while Schilbe mystus had the least concentrations. Variations in the parameters determined were found to be statistically significant (P< 0.05). Based on the result obtained, the levels of the elements under study in the three species were within tolerance limits that are safe for human consumption.
