Experimental studies using live, intact organisms continue to play an essential role in developing knowledge and better understanding of life processes, life forms, and the environments in which they occur. The enormous evolutionary radiation of fishes comprises at least 27,000 species (Nelson 2006). Fishes exist in a multitude of forms and have many unique physiological, behavioral, and ecological specializations. Fishes occupy a variety of niches in virtually every kind of aquatic habitat. Understanding their biology cannot be accomplished in the absence of experimentation with live, intact animals.
Among the reasons for studying fishes are the following: fishes are useful indicators of environmental quality and ecological integrity; fishes provide an important source of food for many of the world’s humans and terrestrial animals and are an important source of food for other aquatic animals; fish are an important part of aquatic environments and ecological systems; catching and observing fishes are very popular and economically important recreational and commercial activities for millions of people around the world; the unique adaptations and physiological specializations of fish make them especially suitable for use as physiological and biomedical models; and the human endeavor to understand the roles that various organisms play in the earth’s ecosystems must include accurate and detailed knowledge of the biology of fishes.
The diversity demonstrated by the 27,000+ species of fishes creates many opportunities for new research, but it also makes the task of developing research protocols that would apply to all species and all circumstances impossible. Instead, broad guidelines building on the most current, scientifically valid information are provided in the Guidelines for interpretation and application by various investigators who frequently are the authority on the species or systems involved in their studies. Ultimate responsibility for the ethical and scientific validity of each study and the methods employed rests with the investigator; however, government agencies, reflecting the beliefs and values of the citizenry and acting on their behalf, often require that investigators follow codes which prescribe acceptable strategies, techniques, facilities, conditions, and post-experimental disposition of animals used in research.