Aquatic ecosystems provide far diverse habitat and the inhabiting biota but our interest in them is too recent and hence knowledge about them is extremely small. The aquatic systems harbour organisms varying from small microbes to largest mammals on globe, the blue whale. With this kind of biodiversity living in aquatics, very little attention was paid till recently when man realized that land is becoming a linking factor and produce from agriculture may not suffice to meet the needs of society. The so made realization gave birth to aquaculture, the culture of aquatic organisms under controlled conditions. Hence fish (fin fish) along with some other organisms (animal and plant) were selected as good candidates for capture as well as culture to serve as food. Fish with exceptionally wide diversity comprises of more than 20,000 living species need to be understood and finding the lead this introductory book whose contents provide material to acquaint the reader with capturing (methods evolved over the period), preserving (for studies and eating) and knowing (identifying) fish is being placed for reader. The contents are projected in a very simple language, scientific terms explained and discussed for their use in day-to-day life, made to assess the freshness/quality of fish available in market and stage developing larvae after hatching to be selected for introduction in the ponds for culturing are the issues that have been dealt in this book for readers who may happen to be the students of fishery science, casual readers or even house wives interesting in purchase and cooking of fish.'