Chromatophores are pigment containing cells found in many animals. In fishes they occur in the scales and the dermal layer of the skin .
The video shows the effect of epinephrine on scale chromatophores. Click the YouTube link for more details. More information on chromatophores.
There are a number of different kinds of chromatophores. They are divided into the following groups based on their colour under white light: xanthophores (yellow), erythrophores (red), iridophores (reflective / iridescent), leucophores (white), melanophores (black/brown) and cyanophores (blue). More information.
Mark McGrouther , Collection Manager, Ichthyology