High male incidence and evolutionary implications of triploid form in northeast Asia Carassius auratus complex

► An high triploid male incidence (23%) was found in Carassius auratus of northeast Asia. ► A total of 61 distinct tf alleles and 35 mtDNA CR haplotypes were revealed. ► Higher genetic diversity and divergence were confirmed in triploids than in diploids. ► Identical genetic background between triploid males and females was demonstrated. ► Evolutionary implications and roles of triploid males in population were suggested.