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Guideline for Use of Ice Water Immersion for Euthanasia of Temperature Sensitive Small Tropical Fish
The TAMU IACUC considers the recommendations of the 2000 AVMA Panel on Euthanasia in review of all proposed forms of euthanasia for all species. However, if scientific justification is provided for a mode of euthanasia that, although not in the AVMA recommendations, is shown to be effective and humane and to cause the least amount of animal suffering as necessary, the IACUC may approve alternate modes of euthanasia.
TAMU scientists have demonstrated to the IACUC that small tropical fish that are sensitive to temperature change may be humanely euthanized by immersion in an ice water bath. Demonstrations with Danio rerio (Zebrafish) have shown that the proper use of ice water immersion results in a quicker and visibly less agitated response from the animal. The IACUC will approve ice water immersion as a form of euthanasia for Zebrafish, and if evidence is provided for other small tropical species*, will approve on a case-by-case basis.
Several practices must be followed in order to assure humane euthanasia and to ensure IACUC approval of the procedure:
1) An ice water slurry should be prepared in advance to ensure appropriate temperature of the water has been reached, a thermometer should be used to determine when 4o C;
2) Fish should not come in contact with blocks of ice, therefore crushed ice is recommended;
3) Fish should be added to the bath in numbers low enough to ensure that the bath temperature does not rise significantly above 4o C;
4) Crushed ice should be added as needed to maintain ice water bath temperature;
5) Fish should be carefully observed to ensure death has occurred;
6) An additional procedure such as decapitation is recommended to ensure death; however, if scientifically impractical, the criteria that will be used to assure death should be clearly explained.
*Note: Investigators are required to obtain IACUC approval prior to trials on other species of fish.