The book on "General Ichthyology" deals with air-breathing fishes which have evolved on several occasions. Evolution of the first bony fishes during the late Silurian and Devonian period produced two new features, lobe fins and the lung fishes. Animals inhabiting the water/air interface show many morphological and physiological adaptations designed with different types of function in that unique environments. In the present age there are new challenges. These include climatic change and contamination of the environment by anthropogenic activities. The subject matter has been delineated in 13 (Thirteen) chapters: Evolutionary Biology, Origin of Fishes, Evolution of Air-breathing Habit in Vertebrates, Morphometrics of the respiratory organs, Evolutionary Transformations of the Respiratory Islets of Air-breathing Organs in Teleostean Fishes, Chloride cells in the Gills of Fresh water teleosts, Respiratory Surface Area Metabolism relationship in Air-breathing Fishes of India, Water/Air Transition in Biology, Structure of the heart of Amphipnous cuchia and their vasculature of the head and respiratory organs. Histochemistry and Functional Organisation, Fine Structure of the Respiratory Organs, Cytology of Macrophages in normal and mercury treated air-breathing fish, Oxygen Uptake and Phylogeny. The book will interest students and research workers in the filed of General Ichthyology.