Sailfish Hunting a Sardine Bait Ball. Sailfish can appear in a startling array of colors, from subdued browns and grays to vibrant purples and even silver. Their body colors are often highlighted by stripes of iridescent blue and silver dots. Sailfish can change their colors almost instantly, since the change is controlled by their nervous system. Nerves send signals to specialized cells called chromatophores and iridophores, which are found mainly in the skin's dermis layer.