Effect of Extended Galvanonarcosis on Behavior of Rainbow Trout, Salmo gairdneri, and Channel Catfish, Ictalurus punctatus

Yearling rainbow trout, Salmo gairdneri, and channel catfish, Ictalurus punctatus, were subjected to 0.5- and 3-h periods of narcosis using continuous direct current. Galvanonarcosis treatments decreased the immediate individual and group activity in both species of fish. Twenty-four hours after treatment, all fish except trout narcotized for 3 h recovered to levels of individual and group activity equivalent to those of untreated fish. Photonegative response was strong in both fish species and was not influenced by galvanonarcosis treatments. Trout narcotized with direct current were more vulnerable to predation than untreated fish; susceptability increased with increasing treatment periods. The potential of extended galvanonarcosis as a fish immobilization technique is strong. Key words: galvanonarcosis, behavior, extended narcosis, direct current, rainbow trout, channel catfish, photonegative, activity, prey vulnerability, immobilization