This chapter emphasizes the ecological responses of fishes to spatial and temporal variation in tropical stream habitats. It also discusses the steps to alleviate human impacts and restore degraded streams to protect the species of the fish. It reveals that freshwater fishes comprise 25% of the vertebrate species on earth. The South and Central American rivers and streams contain the greatest number of species on Earth, with recent estimates ranging as high as 8000 and 25% of global fish species richness. The highest fish species richness in the Neotropics is within the Amazon Basin. The ultimate environmental driver for variations in habitat quality and quantity, and hence breeding events, is probably stream hydrology. Tropical stream fishes occupy almost the entire spectrum of trophic niches that can occur in aquatic communities. Aquatic invertebrates are important food sources for stream fishes throughout the tropics. Terrestrial plants tissues, especially flowers, fruits, and seeds are very important resources for fishes in tropical streams. The primary threat to the ecological integrity of tropical streams and the long. -term survival of their fish faunas is degradation of watersheds by a variety of human activities. The largest impact is from deforestation and conversion of land to agriculture besides over-fishing, dam construction, use of pesticides and herbicides, and introductions of exotic species, etc. Protection of vegetation cover, maintenance of the integrity of riparian zones, and reductions in point. - and non. -point. -source pollution are essential components of conservation and management strategies for stream fishes. 2008 Elsevier Inc. All rights reserved.
