biostudies-literatureBorghezan EAConselho Nacional de Desenvolvimento Científico e TecnológicoCoordenação de Aperfeiçoamento de Pessoal de Nível SuperiorMinistry of Education, Culture, Sports, Science and TechnologyFundação de Amparo à Pesquisa do Estado do Amazonase0222880https://www.ebi.ac.uk/biostudies/studies/S-EPMC6764797biostudies-literatureUnknown14(9)In the absence of constraints, preference for larger mates is expected to evolve, as larger individuals are typical of higher potential fitness. Large females are often more fecund and carry larger eggs (which result in higher number and better quality of offspring), whereas large males usually have more conspicuous ornaments and are better at defending resources. However, intrasexual competition can constrain the access to larger partners, especially when opportunities for mate takeover abound. Here we investigate the relationship between individual's size and mate choice in relation to one's own size and their respective mate's size using the sailfin tetra, a sexually dimorphic Amazonian fish species. We show that ornaments of larger males are exponentially more conspicuous, and larger fPloS oneSomeone like me: Size-assortative pairing and mating in an Amazonian fish, sailfin tetra Crenuchus spilurus.PMC6764797#313183/2014-7#183957#313999/2017-1005/2018Pinto KDSZuanon JPires THDSBorghezan EAfalseSomeone like me: Size-assortative pairing and mating in an Amazonian fish, sailfin tetra Crenuchus spilurus.In the absence of constraints, preference for larger mates is expected to evolve, as larger individuals are typical of higher potential fitness. Large females are often more fecund and carry larger eggs (which result in higher number and better quality of offspring), whereas large males usually have more conspicuous ornaments and are better at defending resources. However, intrasexual competition can constrain the access to larger partners, especially when opportunities for mate takeover abound. Here we investigate the relationship between individual's size and mate choice in relation to one's own size and their respective mate's size using the sailfin tetra, a sexually dimorphic Amazonian fish species. We show that ornaments of larger males are exponentially more conspicuous, and larger f2019-01-01T00:00:00Z20192025-04-21T23:26:57.928Z2019-10-16T07:09:47ZS-EPMC67647973156072510.1371/journal.pone.0222880