The marine environment of the Red Sea coast of Yemen Republic is subjected to contamination by pollutants, mainly heavy metals, from untreated domestic, industrial and agricultural waste water, in addition to run-off during rainy seasons, ship and shipment activities, oil transportation, oil spillage and atmospheric fallout. The present book assesses fish biological responses of exposure and effects of metal pollution at several coastal sites facing different levels of anthropogenic activities along the Red Sea coast of Hodeida governorate using a set of biomarkers. The hazard index was also calculated as an indicator of human health risks associated with consumption of fish edible tissues.