Metamorphosis and puberty are two major events of postembryonic development. Puberty corresponds to the acquisition of the capacity to reproduce in all Vertebrates and occurs only once in the life cycle. Metamorphosis involves morpho-physiological and behavioral changes, which allow the transition from one developmental stage in a specific environment to the next stage in a different environment. Unlike puberty, metamorphosis occurs only in some species. Larval metamorphosis or "primary metamorphosis", exemplified in Amphibians, also occurs in some teleosts such as eels and flatfish. Other less drastic developmental changes are encountered in some migratory teleosts: smoltification in salmons and silvering in eels, which are referred to as "secondary metamorphosis". Puberty is triggered by the gonadotropic axis (brain gonadotropin-releasing hormone, pituitary gonadotropins, gonadal steroids), a scheme largely conserved in Vertebrates, even though additional controls may occur such as the dopaminergic inhibition of gonadotropins in the eel. Amphibian larval metamorphosis is induced by the thyrotropic axis (brain corticotropin-releasing hormone- instead of thyrotropin-releasing hormone-, pituitary thyrotropin and thyroid hormones), which is likely also the case for teleost (eel, flatfish) larval metamorphosis and salmon smoltification, even if more studies are required. In contrast, we revealed a potential key-role of the gonadotropic axis in the induction of eel silvering, making it a pubertal rather than a metamorphic event. This suggests independent recruitments of gonadotropic and thyrotropic axes for the control of secondary metamorphosis during teleost evolution, with remarkable evolutionary convergences in the target tissues and morphogenetic actions of TH and sex steroids.