title: Effectiveness of recommended euthanasia methods in larval zebrafish (Danio rerio).
abstract: The popularity of zebrafish and its use as a model organism in biomedical research including genetics, development, and toxicology, has increased over the past 20 y and continues to grow. However, guidelines for euthanasia remain vague, and the responsibility of creating appropriate euthanasia protocols essentially falls on individual facilities. To reduce variation in experimental results among labs, a standard method of euthanasia for zebrafish would be useful. Although various euthanasia methods have been compared, few studies focus on the effectiveness of euthanasia methods for larval zebrafish. In this study, we exposed larval zebrafish to each of 3 euthanasia agents (MS222, eugenol, and hypothermic shock) and assessed the recovery rate. Hypothermic shock appeared to be the most effective method for euthanizing zebrafish at 14 d after fertilization; however, this method may not be considered an efficient method for large numbers of larval zebrafish. Exposure to chemicals, such as MS222 and eugenol, were ineffective methods for euthanasia at this stage of development. When these agents are used, secondary measures should be taken to ensure death. Choosing a euthanasia method that is effective, efficient, and humane can be challenging. Determining a method of euthanasia that is suitable for fish of all stages will bring the zebrafish community closer to meeting this challenge.
authors: Charles River Laboratories, National Institutes of Health, Bethesda, Maryland, USA.
authors: Jennifer L
authors: JL
authors: Strykowski
authors: Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA. schechj@dir6.nichd.nih.gov.
authors: Joseph M
authors: JM
authors: Schech
mesh_terms: D000818:Animals; D005054:Eugenol / Q000008:administration & dosage; D037901:Euthanasia, Animal / Q000379:methods*; D007035:Hypothermia / Q000662:veterinary; D007814:Larva; D015027:Zebrafish / Q000254:growth & development
chemical_list: D005054:Eugenol
references: PLoS One. 2014 Feb 04;9(2):e88030
references: 24505365
references: ILAR J. 2012;53(2):192-204
references: 23382350
references: J Exp Biol. 2002 Jun;205(Pt 12):1787-94
references: 12042337
references: PLoS One. 2013 Sep 23;8(9):e73773
references: 24086294
references: Zebrafish. 2004;1(1):46-53
references: 18248205
references: Comp Biochem Physiol A Mol Integr Physiol. 2007 Oct;148(2):463-9
references: 17643329
references: Pain. 2009 Jul;144(1-2):84-94
references: 19376653
references: J Am Assoc Lab Anim Sci. 2009 Nov;48(6):785-9
references: 19930828
references: J Vet Pharmacol Ther. 1997 Oct;20(5):333-49
references: 9350253