The Mississippi River embayment, the Mobile River basin, and numerous coastal streams and rivers of southeastern North America together support one of the Earth's richest temperate freshwater biotas.
The headwater streams and rivers of the Yangtze River in central China are also extremely diverse (recognized as a large river major habitat type in this analysis). Secondary centers of temperate diversity occur in the rivers and streams of southeastern North America, the western coast of North America, and the Russian Far East.
Several freshwater biotas on islands are highly distinctive, including those of Madagascar, New Guinea, the Greater Sundas, the Greater Antilles, Sri Lanka, and New Caledonia. The Southwest Australian Rivers and streams ecoregion is a center of endemism, while also harboring a number of primitive higher taxa and several species with highly unusual freshwater life histories.
Rivers and streams along the Gulf of Guinea harbor some of the richest and most endemic riverine freshwater biotas in Africa. The Salween River in Vietnam is recognized for its rich and endemic freshwater fish fauna.