Methods for Fish Biology

Chapter 8: Anesthesia, Surgery, and Related Techniques

Robert C. Summerfelt and Lynwood S. Smith


Anesthetics are chemical or physical agents that, with increasing exposure or concentration, first calm (sedate) an animal, then cause it successively to lose mobility, equilibrium, consciousness, and finally reflex action. In fisheries and aquaculture, the major use of anesthetics is to reduce the activity of fish during transportation and to immobilize fish so they can be handled more easily. Anesthetics, which eliminate the sensation of pain and relax the somatic muscles, also are widely used in various experimental studies to avoid suffering by the fish and to reduce the effect of trauma on the physiological variables under study. Fish surgery requires use of anesthesia, as well as aseptic techniques and antibiotics to prevent infection of the wound. Anesthesia and surgery are integral tools of many experimental studies in general physiology, endocrinology, and pharmacology.

We begin this chapter with a review of fish anesthesia, including definitions of terms, the nature of anesthesia, properties of many kinds of chemical and physical anesthetics, physiological effects of anesthetics, and some regulatory issues related to the use of chemicals on fish. We then outline the basic concepts of fish surgery, including use of anesthetics, instruments, and suture materials, and the procedures for pre- and postoperative care. Injection techniques and urinary cannulation are described because they are useful procedures that are not included elsewhere in this book.

The first use of general anesthesia for human surgery in the USA was an application of ether, in about 1842 (Considine and Considine 1984) or 1846 (Davis 1968). Ether was also the first chemical anesthetic used on fish in the USA, in about 1939 (Griffiths et al. 1941). Ether was still used on fish in the 1960s by Russian scientists during surgery on digestive tracts (Krayukhin 1964).