Fish stock density in the Okavango Delta seems not to be as great as in other sub-tropical and tropical floodplain ecosystems. This may partly be due to obvious constraints such as nutrient deficient water or habitat unpredictability, and it has been suggested that a temporary predator imbalance has been involved. Another contributory factor which may be peculiar to systems with a delayed flood cycle, is that the flood is largely withheld until after the best season for fish growth. This paper describes Okavango fish communities as a whole and discusses several mechanisms which appear to be important in determining fish stocks.