Abstract

 Water and fish samples were collected monthly from each of the four sampling Sites from August to September 2019 with the aid plastic bottles, hook and line and a gura trap from river Ngadda, Maiduguri, Borno state. A total of 16 fishes belonging to Clarias garipienus were sampled throughout the sampling periods. One fish from each station was dried before digestion and other was digested in its fresh form. The samples were transported to Soil Science Laboratory, Faculty of Agriculture, university of Maiduguri for digestion. Nitric-Perchloric acid (HNO3-HClO4) digestion method was carried out as recommended by Association of Analytical Communities (AOAC, 1990). Digested samples were transported to Chemistry Laboratory, National Institute for Freshwater Fisheries Research, New Bussa, Niger state, Nigeria.

The results obtained from this study were 0.016-0.352mg/l and 0.013-0.363mg/l in August and September for cadmium (Cd) in water samples, 0.015-0.617 mg/l and 0.038-0.505 mg/l, 0.031-0.655mg/l and 0.044-0.535mg/l in August and September for cadmium (Cd) in fresh and dried fish samples. Lead (Pb) below detection limit and 0.014-0.016mg/l for water samples, 0.280-0.538mg/l and 0.285-1.538mg/l for fresh and dried fish in August and September. Iron (Fe) 0.264-2.429mg/l and 0.273-2.447mg/l for water, 2.569-13.70mg/l and 7.104-14.723mg/l for fresh and dried fish in August and September. Chromium (Cr) 0.004-0.094mg/l and 0.036-0.237mg/l for water samples, 0.196-0.680mg/l and 0.126-0.446mg/l for fresh and dried fish, in August and September respectively. From the results obtained, it can be concluded that, the concentrations of Cd, Pb, Fe and Cr from water samples were found to contain different levels of metals concentrations which at most of the stations were above the WHO/FAO permissible limits.To reduce addition of heavy metals to aquatic ecosystems, sewage and refuges disposal into the river should be reduced. Further research should be conducted on other heavy metals for consumers’ safety.