Carbon dioxide has been used as a fish anesthetic for many years. It is readily available in the form of Alka-Seltzer™, which when added to water at a rate of 3 tablets per 400 ml produces an equilibrium of carbon dioxide, bicarbonate, and carbonic acid. Despite its ease of use and lack of toxic residues this method of anesthesia is stressful as it alters blood gases and acid-base balance within the animal (Iwama and others 1988). Alternative anesthetics should be used.