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NC3Rs: National Centre for the Replacement Refinement & Reduction of Animals in Research

Zebrafish welfare

Guidance, information and recommendations for those working with zebrafish.

Refining housing and husbandry

Expert reports have been compiled to provide guidance on the following aspects of zebrafish care within a research environment [1,2]:

  • Housing and husbandry (see [2] Table 1 for summary).
  • Transportation and reception.
  • Breeding and identification.

See [3] for a review into the physical and social factors that contribute to zebrafish welfare, and how understanding the natural history of zebrafish can inform welfare refinements and improvements in experimental science.  

See [4] for a review of the evidence and challenges related to environmental enrichment and laboratory zebrafish.

Refining procedures

See Chapter 5 of [1] for guidance and recommendations on a range of scientific procedures involving zebrafish. See the below publications for information on other potential refinements:

  • A refined protocol for VIE tagging [5].
  • A protocol for skin swabbing to collect DNA for zebrafish genotyping [6].
  • Validation of morphine for reducing pain in zebrafish that have undergone heart cryoinjury, without affecting the regeneration of heart tissue [7].
  • Validation of lidocaine hydrochloride buffered with sodium bicarbonate and ethanol for euthanasia of adult zebrafish [8] and embryos and larvae [9].
  • Discussions on analgesia, anaesthesia, and euthanasia in zebrafish [10,11].
  • An investigation of suitable protocols for repeated anaesthesia of juvenile zebrafish [12].

Community and databases

Zebrafish in Tech3Rs

Tech3Rs is our regular newsletter providing animal technicians with the latest news from the NC3Rs. Each issue features updates on recent advances in the 3Rs and highlights new resources, research and events that we think will be of interest to animal technicians, including information relevant for those working with zebrafish.

Additional resources


  1. RSPCA (2011). Guidance on the housing and care of zebrafish Danio rerio.
  2. Aleström P et al. (2019). Zebrafish: housing and husbandry recommendations. Laboratory Animals 54(3): 213-224. doi: 10.1177/0023677219869037
  3. Lee CJ et al. (2022). Improving zebrafish laboratory welfare and scientific research through understanding their natural history. Biological Reviews. doi: 10.1111/brv.12831
  4. Stevens CH et al. (2021). Enrichment for laboratory zebrafish—a review of the evidence and the challenges. Animals 11(3): 698. doi: 10.3390/ani11030698
  5. Rácz A et al. (2021). Identification of individual zebrafish (Danio rerio): A refined protocol for VIE tagging whilst considering animal welfare and the principles of the 3Rs. Animals 11(3): 616. doi: 10.3390/ani11030616
  6. Tilley C et al. (2021). Skin swabbing protocol to collect DNA samples from small-bodied fish species. F1000Research 10(1064): doi: 10.12688/f1000research.73115.1
  7. Lelek S et al. (2020). Morphine alleviates pain after heart cryoinjury in zebrafish without impeding regeneration. bioRxiv. doi: 10.1101/2020.10.01.322560
  8. von Krogh K et al. (2021). Screening of anaesthetics in adult zebrafish (Danio rerio) for the induction of euthanasia by overdose. Biology 10(11): 1133. doi: 10.3390/biology10111133
  9. JP Mocho et al. (2022). A multi-site assessment of anesthetic overdose, hypothermic shock, and electrical stunning as methods of euthanasia for zebrafish (Danio rerio) embryos and larvae. Biology 11(4): 546. doi: 10.3390/biology11040546
  10. Collymore C (2020). Anesthesia, analgesia, and euthanasia of the laboratory zebrafish. In: The Zebrafish in Biomedical Research. Academic Press.
  11. Köhler A et al. (2022). Analgesia, anesthesia, and euthanasia in zebrafish. In: Laboratory Fish in Biomedical Research. Academic Press.
  12. Owen JP and Kelsh RN (2021). A suitable anaesthetic protocol for metamorphic zebrafish. PloS one 16(3), e0246504. doi: 10.1371/journal.pone.0246504