Fish were selected as a common target sample for a collaborative study of FNCA(Forum for Nuclear Cooperation in Asia)-NAA(neutron activation analysis) project in 2011. Six Asian countries took part in this work. Fish samples were purchased from commercial markets and prepared by following an agreed protocol. Toxic and essential elements in the prepared samples were determined by NAA. The concentration levels of As, Hg in many fish samples have higher values than the regulation ones. The fish contamination by heavy metals should be monitored continuously for human health.