Abstract

Euthanasia of individual or small groups of fish in the aquarium setting is most often performed using an overdose of anesthetic drugs. However, there are a number of situations where the use of such chemicals is undesirable, due to disposal concerns or intended use of the culled fish as a food source for other animals. Historically, some facilities have used rapid cooling (ice baths) in these situations, which is not an approved humane method per the AVMA Guidelines for the Euthanasia of Animals. In large-scale aquaculture facilities, mechanical devices have been developed to allow rapid humane slaughter of large numbers of fish, but this is not practicable for most aquarium facilities.

A commercially available spring-powered penetrating captive bolt device was investigated as an option for rapid euthanasia of individual or small groups of moderate-sized fish commonly seen in aquaria. The stainless steel handheld device is manufactured for the humane slaughter of large poultry, and when utilized on appropriately-sized fish, resulted in instantaneous destruction of the brainstem and death. To ensure proper placement of the device, initial trials were performed on the species to be culled (trout, bass, sunfish) with individuals under deep chemical anesthesia. In cases where the brainstem was not adequately destroyed by the penetrating bolt, the concussive force applied appeared adequate to render the fish insensible and allow immediate pithing and destruction of brain tissue through the hole created in the braincase.

* Presenting author