Studies on tropical freshwater zooplankton which commenced in the mid-19th century have been intensified during the past twenty years or so . The whole region, barring a few areas, has been investigated, including very recently tropical Australia . The widely scattered literature is briefly summarized with comments . Some general distributional patterns are emerging . There is a dearth of ecological studies especially on seasonality and production . Systematics lags behind the North Temperate zone in most tropical regions .