As aquaculture continues to expand there is a need for greater knowledge of medicinal treatments both for the prevention and treatment of disease and for the economic husbandry of fish. This guide is written for a worldwide readership. It is a reference manual for anyone involved in the selection of medicines for administration to fish. It should also prove useful to administrators concerned with the legal control of aquaculture. The first part covers issues which affect all medicine's methods of administering drugs to fish, the various aspects of safety and the relevant legislation in countries with important aquacultural industries. Subsequent parts review the range of available medicinal substances and present knowledge of the pharmacology and methods of use for each. Particular attention is given to safety issues - for the fish, for the person administering the medicine, for the consumer of medicated fish and for the environment.