Body colouration, or pigmentation, plays an essential part in every animal’s survival (e.g., predator avoidance, reproductive success, or social interactions). Pigmentation patterning systems are of great interest not only in ecology, but also for development and evolution, all aiming to understand the wide variety of patterns seen in living animals. This chapter summarizes the current knowledge on the development, role, and diversity of colour patterns in anemonefish. The colour patterns of most adult anemonefish species are rather similar, comprising zero to three vertical white bars with a black edge on an orange, red, or black body background. Even though the patterning system remains elusive this chapter will describe available information on anemonefish colour patterns, including contributing pigment cells, ontogenesis, functions, and variation both in natural and domesticated stocks.