Microphthalmia-related transcription factors (MITF) are closely related to the formation of melanocytes (melanophores). The casper mutant zebrafish is a double-gene mutant zebrafish strain (mitfaw2/w2; roya9/a9) bred by crossing nacre and roy orbison. The observation of fin, scale and early body color development of mitfa-mutated casper zebrafish in this paper confirmed that there were no melanocytes in anal fin, dorsal fin and dorsal scale of casper zebrafish, and no melanocytes were generated during the early body color development. The recombinant plasmid of mitfa overexpression was constructed and microinjected into the fertilized eggs of casper zebrafish. Melanocytes were observed in the head, back and abdomen of the injected group. The results further confirmed that mitfa plays an important role in the formation of fish body color, especially in the formation of melanocytes. At the same time, the preparation of mitfa over-expressing casper zebrafish also provides a material platform for in-depth research on the molecular regulation of fish body color.