http://www.bvzs.org/euthansiaguidelinesfish.htm
British Veterinary Zoological Society
Guidelines for Acceptable Methods of Euthanasia for Zoo, Exotic Pet and Wildlife species
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British Veterinary Zoological Society [BVZS], 7 Mansfield Street, London W1M 0AT, UK.
http://www.bvzs.org
No. 2: Ornamental Fish
[SNIP]
Suggested methods of choice:
The following methods are rapidly effective and straightforward to perform.
· Overdose of a soluble anaesthetic agent added to the water (MS222, Benzocaine [in acetone /alcohol], Eugenol [clove oil])
· Intravenous overdose of anaesthetic agent, primarily pentobarbitone.
· Trauma sufficient to induce complete and instantaneous loss of brainstem activity (e.g. shooting, captive bolt, massive blunt trauma, cervical dislocation or fracture)
· Dropping into liquid nitrogen to provide near instantaneous complete freezing (individuals less than 1cm max diameter only)
Methods considered
unacceptable:
The following methods have been suggested for ornamental fish euthanasia in the past but should now be considered ineffective or unacceptable:
· 'Asphyxiation' (simple removal from water preventing respiratory exchange)
· Freezing (excepting method suggested above)
· Use of other anaesthetic agents added to the water (Pentobarbitone, Isofluorane, Halothane)
· Trauma (other than cranial & cervical trauma as described above)
· Carbon dioxide by non-commercial methods (Alka-seltzerŪ tablets, soda-streamŪ carbonation)