In the post genome era,a major goal in molecular biology is to determine the function of the many thousands of genes present in the vertebrate genome.The zebrafish (Danio rerio) provides an almost ideal genetic model to identify the biological roles of these novel genes,in part because their embryos are transparent and develop rapidly.The zebrafish has many advantages over mouse for genome-wide mutagenesis studies,allowing for easier,cheaper and faster functional characterization of novel genes in the vertebrate genome.Many molecular research tools such as chemical mutagenesis,transgenesis ,gene trapping,gene knockdown,TILLING,gene targeting,RNAi and chemical genetic screen are now available in zebrafish.Combining all the forward,reverse,and chemical genetic tools,it is expected that zebrafish will make invaluable contribution to vertebrate functional genomics in functional annotation of the genes,modeling human diseases and drug discoveries.