Seahorses are globally threatened. In Brazil there are three species: Hippocampus reidi, Hippocampus patagonicus and Hippocampus erectus. The Brazilian Ministry of the Environment  classifies them as vulnerable, being protected by PAN Corais (National Action Plan for the Conservation of Coral Environments). Using snorkeling diving activities, inventory and monitoring of seahorses were developed to mapping the occurrence of species and its habitats during last 17 years. Seahorses occurred from north to south of Brazil, inhabiting mangroves, estuaries, bays, environments of continental rocky coastlands, continental and oceanic islands. Hippocampus reidi had this same general occurrence with marked distribution from the northeast (Maranhão) to the south (Santa Catarina) region; H. erectus had the same occurrence as H. reidi with a marked distribution from the northeast (Rio Grande do Norte) to the southeast (São Paulo) region. Hippocampus patagonicus was widely distributed between the southeast (Rio de Janeiro) and the southern (Rio Grande do Sul) region. Although Brazil has 257 marine and coastal Protected Areas (PAs), the map of distribution of seahorses shows that the PAs does not ensure the conservation of the species, mainly of H. patagonicus, whose populations are concentrated outside the PAs. Hippocampus reidi is present in marine PAs, and H. erectus needs further studies, including mapping.Our results indicate the need to evaluate public environmental policies in Brazil and suggest that H. reidi should be included in the PAN Manguezal (National Action Plan for the Conservation of Mangrove Environments), as we do not yet know if the marine populations are genetically the same to those of the mangroves. In the case of H. erectus its search in natural environments is needed, and for H. patagonicus, a conservation proposal in the light of new evidence of its restricted distribution is necessary.