Abstract <p>Teleosts have an outstanding diversity of pigment patterns among vertebrates. Studying the role of hormones as mediators of morphological trait variation, including pigment patterns, contributes to our understanding of the involvement of endocrine regulatory mechanisms in the evolution of fish. In this work, using three model fish species (<i>Amatitlania nigrofasciata</i>, <i>Danio rerio</i> and <i>Poecilia wingei</i>), I review the influence of alterations in thyroid hormone signaling on the development of adult pigment patterns. The evidence accumulated to date suggests that thyroid hormones are involved in the development of chromatophores and intercellular interactions and also, through various mechanisms, induce a wide range of ontogenetic programs, leading to increased diversity with the appearance of novel coloration phenotypes.</p>