Pigmentation enhancement techniques during ornamental fish production

The ornamental fish industry has continued to flourish since eighteenth century with increased fascination by enthusiasts in the striking body colours and patterns displayed in the fishes, a beneficial outcome of rigorous selective programmes. The expression of these pigmented colours is the result of the differentiation and orientation of specialised chromatophores located within the dermal layer. The different types of chromatophores found in many ornamental fish species, are the basis of the unique colour hues and patterns. This review discusses the current approaches for enhancing the body pigmentation and pattern of ornamental fishes. Two factors are considered to be the main drivers of body colour regulation: feed additives (pigments) and rearing environment setup, i.e. tank colour and light. Potential candidate pigment genes to manipulate the ornamental fish body pigmentation and pattern have been elucidated through mapping of putative regulatory pathways, buoyed by the rapid development of next generation sequencing technologies. The effects of feed additives, tank background colour and light on various ornamental fish species, and regulatory pathways of involved genes offer valuable insights for enhanced variety production prior to genetic engineering and are herein discussed. It is hoped that the systematic analysis of the current knowledge in this review would be a boon for the ornamental fish community to step up efforts to boost the ornamental fish breeding industry.