CHARACTERIZATION AND QUANTIFICATION OF FATTY ACID AND HEAVY METALS IN FARM RAISED AND WILD CLARIAS GARIEPINUS (BURCHELL 1822)

Abstract

The lipid, fatty acid profile and heavy metals concentration of wild and farm-raised Clarias gariepinus were assessed and compared with a view to investigate their level of concentration in relation to possible carcinogenicity. A total of twelve experimental fish, C. gariepinus, were collected from River Ogbese and a commercial fish farm in Akure, Ondo State, Nigeria. Whole fish fillet and tissues from the Pectoral, Pelvic and Caudal regions of the fish were collected in duplicates from the experimental fish and subjected to fatty acid analysis using Gas Chromatography- Mass Spectrometry. Parts of the samples collected for the whole fish fillet were also subjected to lipid profile analysis. Determination of heavy metals; Arsenic (As), Cadmium (Cd), Chromium (Cr) and Lead (Pb) in the tissue of the collected C. gariepinus was carried out in triplicate by Atomic Absorption Spectrophotometry, AAS, using standard analytical protocols for heavy metal determination. Data obtained, for lipid and fatty acid profile in the tissue of C. gariepinus collected from the two locations, were compared by descriptive statistics. One-way analysis of variance and Duncan Multiple test were used to test for significant difference among data obtained from different regions of the fish within the same location. Student’s T-test was also used to compare mean concentration of the assessed heavy metals. Result obtained revealed that Triglyceride and High density lipoprotein cholesterol were highest in farm raised C. gariepinus while total cholesterol was highest in the wild C. gariepinus. Both the highest and lowest percentage concentration of fatty acid were recorded in the whole tissue fillet of the wild species with the highest value recorded for Monounsaturated fatty acid (MUFA) and the lowest value for Polyunsaturated fatty acid (PUFA). Only n-3 fatty acid was detected in this study and the highest concentration was recorded in the pectoral region of the wild fish while the lowest was recorded at the caudal region. However, this was not the case for the farm raised species, where the highest concentration was recorded at the pelvic region while the lowest was recorded in the whole fish. Saturated fatty acid (SFA), MUFA and PUFA concentrations in all the sampling regions were higher in the wild C. gariepinus, although there was only a slight variation in the PUFA concentration in the pelvic region of both the wild and farm raised species. The result of the heavy metals assessed shows no significant difference between the concentration obtained for both the farm-raised and wild C. gariepinus, except for the concentration of lead (0.09 ±0.004a) which was significantly higher in the wild species. The concentration obtained for Cd, Cr and Pb ranged from 0.001-0.002, 0.005-0.009 and 0.016-0.023 for farm-raised C. gariepinus while that of the wild species ranged 0.002- 0.003, 0.009-0.011 and 0.086-0.096 respectively. Arsenic (As) had a constant concentration of 0.001 in all the replicates from both the farm-raised and wild C. gariepinus. The concentrations of all the assessed heavy metals were lower than the standard maximum permissible limit recommended by various International Regulatory bodies/agencies. The concentration of the lipid profile, fatty acid ratio and heavy metals obtained were within acceptable range for healthy consumption by human. Hence, both the wild and farm-raised C. gariepinus are safe and good for human consumption.