According to Krystek and Ritsema (2006), significant differences in Hg levels are found in different seafood species analysed. Fish at high trophic levels in the food chain, like large predatory fish, accumulate more Hg and contain significantly higher concentration levels. Two predatory Brazilian fish samples (red porgy-1 and red porgy-2) and two predatory Spanish fish samples (tuna-3 and swordfish-1) showed the highest levels of total Hg: 1.63 ± 0.04 mg kg1 (red porgy-1), 1.15 ± 0.01 mg kg1 (red porgy-2), 2.33 ± 0.03 mg kg1(tuna-3) and 1.04 ± 0.03 mg kg1 (swordfish-1)