There are four types of pigment cells in fish, including melanocytes, erythrocytes, xanthophores, and iridocytes. AG1478 is a novel inhibitor against Tyrosinase(Tyr). Tyr is a key enzyme in melanin production and it is specifically expressed in melanocytes. In the paper, we studied the ultrastructural observation of four pigment cells and two different shapes of melanocytes in white crucian. We also investigated the effect of AG1478 inhibitors on the early body color development of white crucian. Our data indicate that the AG1478 inhibitor had few effect on the early body color development of white crucian.