Cytogenetic and environmental factors have been reported to cause variations in the genome size within the
species. However, the broad scale genome size variation of a class of vertebrate especially Osteichthyes fishes across the
different climatic zone and habitat conditions hasyet to be documented. In this study, we analyzed the genome size
variation of 285 species of Osteichthyes fishes distributed across the marine and freshwater habitat. We found that
habitat and climatic zone showed a significant pattern of genome size variation, however, the body size, chromosome
number and diversity rate has no strong correlation with the genome size
