Melanophores are pigment cells containing melanin grains that determine the black, brown, and blue-black coloration of fish.
A melanophore differs from a melanocyte in that it is able to move pigment granules (melanosomes) around the cell. Melanophores are found in fish, amphibians and reptiles. Together with iridophores and xanthophores, they form the dermal unit. Melanophores can be innervated (fish, reptiles) and non-innervated (amphibians), depending on this pigment aggregation/dispersion reactions can be either fast (5-10 min) or slow (50-80 min), respectively. Melanophores are involved in the formation of fancy coloration in animals.
Melanophores are sensitive to humoral hormones: melanocyte-stimulating hormone and melatonin. When exposed to the former, the melanophore distributes the pigment throughout the cell (dispersion), and as a result of melatonin action, it collects the pigment in the center of the cell (aggregation).