Cambodian inland fish resources are part of the Mekong system. With 781 known freshwater and brackish fish species, the Mekong Basin has the second highest fish biodiversity in the world after the Amazon Basin in South America. Cambodia itself features 461 freshwater species, plus 468 marine species and 26 species found in both environments. This makes 955 fish species in total. These numbers have increased over time as new species are discovered, and they vary slightly between studies as estuarine or diadromous species are sometimes counted as marine and sometimes as freshwater species.