The aim of the present study was to standardize and to assess the predictive value of the cytogenetic analysis
by Micronucleus (MN) test in fish erythrocytes as a biomarker for marine environmental contamination. Micronucleus
frequency baseline in erythrocytes was evaluated in and genotoxic potential of a common chemical was determined
in fish experimentally exposed in aquarium under controlled conditions. Fish (Therapon jaruba) were exposed for 96
hrs to a single heavy metal (mercuric chloride). Chromosomal damage was determined as micronuclei frequency in
fish erythrocytes. Significant increase in MN frequency was observed in erythrocytes of fish exposed to mercuric
chloride. Concentration of 0.25 ppm induced the highest MN freque