The study measured heavy metal levels in different tissues of six Mediterranean fish species and looked at how fish size relates to metal concentrations. The liver had the highest metal levels, except for iron in the gills of one fish species. Some fish showed very high concentrations of certain metals, like copper in the liver of one species. Overall, most fish had negative relationships between metal concentrations and size, meaning as the fish got bigger, metal levels decreased in some tissues. This suggests that larger fish may accumulate fewer heavy metals.