Bioaccumulation of heavy metals in marine fishes (Siganus sutor, Lethrinus harak, and Rastrelliger kanagurta) from Dar es Salaam Tanzania

Toxic metals that bioaccumulate and magnify along food chains are a concern to human health worldwide. This study determined heavy metal concentrations in three commercial fish species; viz: whitespotted rabbitfish (Siganus sutor), thumbprint emperor (Lethrinus harak), and the Indian Mackerel (Rastrelliger kanagurta) from Kunduchi fish market in Dar es Salaam, Tanzania, assessed potential risks to human health, and the suitability of their fins as a non-destructive monitoring organ. Metal concentrations in fish muscle differed significantly among fish species as a result of their diverse ecological needs, metabolism, feeding habits, and habitats. The results also indicated that fish fin may not be a very good non-destructive monitoring organ for most metals, but can be used selectively for some metals and fish species. The levels of metal intake (aluminum (Al), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb) and zinc (Zn)) in fish muscles were below the FAO/WHO maximum levels for contaminants and toxins in foods for human consumption except for arsenic (As) which were higher than the recommended levels in Lethrinus harakand Rastrelliger kanagurta. It is recommended to reduce the amount of L. harakand R. kanagurta in daily meals of especially fishers and coastal communities who may eat fish up to three meals daily. Recommendation for further studies is provided.