Proximate Composition and Mineral Contents of Farmed and Wild Fish in Kenya

The Kenyan government is promoting fish farming to boost fish supply and reduce rural poverty and malnutrition. This study was carried out to determine the differences between the chemical composition of wild and farmed fish particularly Nile tilapia (Oreochromis niloticus) and African Catfish (Claris gariepinus) species. Wild fish were obtained from City market Nairobi, while farmed fish were obtained from selected ponds in Sagana and Kamulu (Kenya). Proximate composition, mineral and heavy metal content of the fish were determined using standard methods of analysis. Farmed fish contained significantly higher moisture content than the wild fish. Protein content in wild fish ranged from 21.9 – 22.1 % compared to 16.0 – 19.2 % in farmed fish. Fat content in wild fish ranged from 3.0 – 3.8 % compared to 1.9 – 4.8 % in farmed fish and ash from 1.8 – 2.1 % in wild compared to 1.1 – 1.5 % in farmed fish. The concentration of minerals in wild fish ranged from 2.8 – 3.0 mg/100g of iron, 5.5 – 5.6 mg/100g zinc, and 39.9 – 43.8 mg/100g calcium compared to the lower values of 1.9 – 2.4 mg/100g of iron, 28.2 – 37.0 mg/100g calcium and 4.3 – 5.0 mg/100g zinc in farmed fish respectively. Unfortunately, the wild fish was found to contain significantly higher concentrations of heavy metals as compared to the farmed fish (P < 0.05). From the results, it was evident that wild fish were nutritionally superior to the farmed fish but, they also contained significantly higher levels of toxic heavy metals.