Small-sized fish: The largest and most threatened portion of the megadiverse neotropical freshwater fish fauna

Abstract

We introduce the work providing a synthetic description of the diversity and phyletic structure of freshwater fish in the Neotropical Region, especially emphasizing that of Brazil. This is accompanied by a discussion about environments of fish from small to medium sized to large, taking into account how it shaped their respective biologies/ecologies, as well as what they imply for their use by humans. We present, as figures, the results of our exploratory analysis of Brazilian Red Book of Threatened Species of Fauna (2018), focusing on the small-sized ones, with up to 15 cm of standard length. We continue to present the main human impacts in small fish environments, along with those suffered by medium to large fish environments, and then follow by their respective deleterious effects. Finally, we present a general synthesis, reinforcing the enormous importance of small fish conservation and their respective preferred environments, followed by our main conclusions, and possible conservation strategies.