Concentrations of cadmium, mercury, manganese, phosphorus, lead and zinc in samples of Basa fish (Pangasius hypothalmus) and some fresh water fish (Tilapia nilotica, named Bolti and Karmout) collected from Kafer-El-Zayat were determined. Karmout fish contained the highest level of metals where phosphorus level was 3.45 μg/g, lead (1.51μg/g), zinc (1.03 μg/g), cadmium (0.17 μg/g), manganese (0.08 μg/g) and mercury (0.007μg/g). In Bolti fish, phosphorus level was 4.03 μg/g, lead (0.83 μg/g), zinc (0.62 μg/g), cadmium (0.12 μg/g), manganese (0.08 μg/g) and mercury (0.004 μg/g). In Basa fish, phosphorus level was 4.06 μg/g, lead (0.79 μg/g), zinc (0.62 μg/g), cadmium (0.12 μg/g), manganese (0.07 μg/g) and mercury (0.004 μg/g). Cadmium and lead levels in all examined fish were higher than permissible safety level of human use (0.1 ppm). Pre-treatment of fish muscles by acetic acid (5%) for a period of 15 min resulted in marked reduction of metals in these fish. When the Basa fish was immersed in 5% acetic acid, the cadmium level in the flesh was reduced from 0.12 to 0.07 μg/g (41.6%) and lead level was reduced from 0.83 to 0.41 μg/g (51.9%). In Bolti fish, pre-treatment of the fleshy parts by acetic acid reduced cadmium level from 0.12 to 0.07 μg/g (58.3%) and lead was reduced from 0.83 to 0.02 μg/g (24%). The same result was observed in Karmout fish, where pre-treatment with acetic acid lowered the cadmium level from 0.17 to 0.05 μg/g (29.4%) and lead was lowered from 1.51 to 0.82 μg/g (54.3%).
Key words: Basa fish, Tilapia nilotica, Karmout, acetic acid, heavy metals.
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