Abstract

Objective: To study the bioaccumulation of heavy metals from Synodontis clarias (S. clarias) and Chrysichthys nigrodigitatus (C. nigrodigitatus) with their parasitic fauna. Methods: A total of 50 specimens of each fish species (n = 100) were examined. The fishes were subjected to parasitological investigation while 3 g of intestinal tissue of S. clarias and C. nigrodigitatus samples were digested with nitric acid (10 mL). The tissues were then heated until brown fumes disappeared. The samples were allowed to cool and distilled water was added to make up to 50 mL in a standard flask. The filtrate was examined using the atomic absorption spectrometer. The fish hosts were weighed and measured with the aid of digital weighing balance and measuring board, respectively. Results: The Chi-square distribution was significant at 0.01 level (χ2 = 2.16, P < 0.01). A nematode of the family Camallanidae (Procamallanus spp.) was found in S. clarias and a trematode (Siphodera ghanensis) was found in C. nigrodigitatus. The total lengths of C. nigrodigitatus in females and males were (15.05 ± 3.27) cm and (20.35 ± 4.20) cm (P < 0.01), respectively. Also the total lengths of S. clarias in females and males were (21.07 ± 2.80) cm and (20.76 ± 2.37) cm (P < 0.01), respectively. The mean value for the condition factor of both S. clarias and C. nigrodigitatus were more than 2.0. The concentrations of the trace elements in the fishes were Pb > Zn > Mn > Fe > Cd (not detected) and Mn > Zn > Fe > Pb > Cd (not detected), respectively, while in the nematode, Procamallanus spp. and trematode, Siphodera spp. were Pb > Mn > Fe > Zn > Cd and Mn > Fe > Zn > Pb > Cd, respectively. In the water and sediment, the distribution of heavy metals were Fe > Mn > Zn > Pb > Cd and Fe > Mn > Pb > Zn > Cd, respectively. Conclusions: The findings of the concentrations of the trace elements in the aquatic habitat as well as the sediment were below the permissible limit of Federal Ministry of Environment. These findings confirmed that the aquatic habitat was adequate for fishing activity and that the consumption of fish species therein are safe. However, it should be noted that there was bioaccumulation of trace elements in the fish tissues which should not pose any danger to man. Therefore, a regular monitoring of the levels of trace elements in the water body as well as in the fauna should be regularly undertaken.

Authors and Affiliations