Natural history of the flood fishes

Abstract

Ideally the fish fauna of a river system should be investigated from the three principal levels of biological organization — the species, the community, and the ecosystem — if its natural history is to be understood in the broadest terms. The high diversity of the Amazon fish fauna, and lack of sound taxonomical studies for most groups, make the study of communities very difficult in the present state of knowledge. My own approach has been to take a binocular perspective by concentrating on the specific and ecosystem levels, and extrapolating community structure, in a cautious manner, from these polar viewpoints. As for species, the food fishes are an excellent point of departure because of their abundance — hence importance in the ecosystem — and a constant and intensive fishing effort directed towards them helps reveal many ecological patterns, and especially migratory behavior. Before discussing each of the food fish species in detail, I will first present an overview of what is known about their migratory and feeding behavior in relation to the Rio Madeira as a system.