International Journal of Scientific & Engineering Research, Volume 6, Issue 11, November-2015 630 ISSN 2229-5518 IJSER © 2015 http://www.ijser.org Heavy Metal Concentrations of Some Fish Species Consumed in Ozoro, Delta State, Nigeria *C. K Ojebah and K. Emumejaye Department of Science Laboratory Technology Delta State polytechnic, P.M.B 5, Ozoro *Corresponding email: ckojebah@gmail.com Abstract— This study investigated the heavy metal concentration of commonly consumed fish species in Ozoro, Delta State, Nigeria. The four fish samples procured from Ozoro daily market; Tilapia (Oreochromis niloticus), Mud Fish (Clarias anguillaris), Catfish (Ostariophysi Siluriformes) and Croaker fish (Micropogonias undulates) were used in this study. Each of the fish samples were cut into three parts; head, trunk and tail. Samples were then oven dried and ashed in electric furnace at temperature of 450 0 C. The fish parts were digested using Nitric acid/Perchloric acid mixture (2:1). Heavy metal concentration was determined using Atomic Absorption Spectrophotometer (Varian Spectra AA 200 model). Results obtained showed that most of the metals were associated with the head. Zinc was the most dominant metal and ranged from 2.97 - 6.59mg/kg. Copper ranged from 0.94 - 3.13mg/kg; Pb and Cd concentration ranged from 0.06 - 1.36mg/kg and 0.00 - 0.30 mg/kg dry, respectively. The mean concentrations of the metals were below world mean average except lead. The presence of non essential elements (Pb and Cd) in the study calls for concern to the consuming populace of these fishes. Index Terms— Concentration, Fish, Heavy metal, Head , Tail, ——————————  —————————— 1 INTRODUCTION eavy metals are metals of high density usually greater than 5.00 to 6.00 g/cm³ and may have hazardous effects on plants and animal ecosystems when present above concen- trations found naturally (Keepax et al., 2011). Heavy metals are potentially toxic (aluminiun, arsenic, cadmium, antimony, lead and mercury), semi-essential (nickel, vanadium, cobalt) and essential [copper, zinc, selenium, manganese, iron, etc] (Szentmihalyi and Then, 2007). These essential metals can be toxic effects when excessively taken (Tüzen, 2003; Ellias, 2009). Fishes are the most important organisms in the aquatic food chain. They are very sensitive to heavy metals contamination. Fishes are a great source of protein enhanced food the world over (Mansour and Sidky, 2002). Consumption of fish contam- inated with heavy metals can have toxic effects on human health (Mai et al., 2006). Heavy metals once penetrated into the body through food chain may lead to serious diseases (Idzelis, 2007). Ingestion of heavy metals leads to numerous health challenges (Ayeloja et al., 2014).Various studies have been conducted on heavy metal bioaccumulation in the head, trunk and tail of fish collected from different freshwater aquat- ic systems (Asiagwu et al., 2009). The objective of this present study was to determine the occurrence and levels of some se- lected heavy metals (Copper, lead, cadmium and zinc) in head, trunk and tail of the fish, Tilapia, Mud fish, cat fish and crokers commonly consumed in Ozoro, Delta State Nigeria. There has been no reported study on this to the best our knowledge in the area and so this study will serve as a base- line for future references in Ozoro and environs. 2 MATERIAL AND METHODS 2.1. Description of the study area The study was carried out in Ozoro, Delta State, Nigeria. Ozo- ro is a semi-urban town that is fast developing probably be- cause of the state Polytechnic. Ozoro is the administrative headquarters of Isoko North Local government Area and lies between longitude 6°12′58″E and latitude 5°32′18″N (www.wikipedia.org). 2.2. Sampling and Analysis Fish samples were purchased from daily market in the town. The fish were carefully cut into three parts; head, trunk and tail. The various parts were oven dried and thereafter ashed in an electric furnace at 450˚C. 2g of the ashed fish parts were weighed into three separate beakers. 10ml of nitric/perchloric acid, ratio 2:1 were added to the samples and digested at 105˚C for 1hour. HCl and water in the ratio 1:1 were added to the digested samples and the mixture heated for 30 minutes. The digestate was allowed to cool to room temperature and filtered into a 100ml volumetric flask using Whatman (No. 1) filter paper and made up to mark with distilled water. The samples were then analysed for heavy metals (Cu, Pb, Cd and Zn,) using Atomic Absorption Spectrophotometer (Varian Spectra AA 200). 2.3. Statistical Analysis The data obtained were processed statistically and presented as mean ± standard error of mean. Statistical significance of comparison of data was analysed using one way analysis of H IJSER