Hill stream fishes are economically important for their ornamental value.They have high demand in international market for aquarium fish keepers. This book on a hill stream fish, Devario aequipinnatus describes the effect of environmental acid stress at surface micro structural and internal fine structural level through Electron microscopic studies. The book also describes the detailed biology, ecological conditions and water quality necessary for the rearing of the fish in aquarium. The reasons for gradual population decline of hill stream ornamental fish in different parts of the globe are also described in the book. The book also describes the appropriate strategies to be adopted for induced breeding of the fish in aquarium. The book will thus be a practical guide for aquarium fish keepers. Besides this, Fish biologists in general,Cell biologists,Environmentalists,Bio-technologists and researchers from other disciplines will find the book interesting and useful because hill stream fish, Devario and related species are considered to be ideal models for toxicity and environmental stress studies.