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Project grant

Quantifying the potential of skin swabbing as a refinement for DNA sampling of laboratory fish

a zebrafish is held in a hand net and swabbed.

At a glance

Award date
December 2017 - March 2021
Grant amount
Principal investigator
Dr Will Norton


University of Leicester


  • Refinement
Read the abstract
View the grant profile on GtR
NC3Rs gateway article
Read the methods on F1000Research


Project background

Fish are increasingly used in scientific research, with zebrafish the predominant species in biomedical research and species such as sticklebacks typically used for environmental and ecological studies. DNA samples are often required from fish to confirm their genotype, or their sex, before physical characteristics are visible. DNA is often collected via fin clipping, an invasive procedure that is performed under anaesthesia where a small section of the caudal fin is removed. Fin clipping can harm the fish by causing pain and stress, altering physiology, locomotion or behaviour, and increasing the risk of infection.1

Why we funded it

This Project Grant aims to investigate whether the use of skin swabbing for DNA sampling in small laboratory fish, namely the zebrafish and stickleback, represents a refinement to fin clipping, the current standard procedure.   

There are an estimated 3,250 zebrafish facilities worldwide, and approximately 85% use fin clipping as highlighted in a recent NC3Rs publication.2 Dr Norton and colleagues contacted UK zebrafish labs and estimate that each lab conducted a minimum of 500 zebrafish fin clips per year. It is estimated that over 20,000 DNA sampling procedures occur annually in the UK and over 1 million worldwide. These procedures could be refined by using the skin swabbing technique if it is demonstrated as a validated refinement.

Research methods

Dr Norton and colleagues have published a protocol for zebrafish and sticklebacks where swabbing skin mucus is used to collect DNA samples.3 Skin swabbing is less invasive than fin clipping and hypothesised to be a refinement for DNA sampling. To test this hypothesis, this project will compare the two techniques to quantify the welfare benefits of swabbing compared to fin clipping. Various components of both protocols will be analysed for their effects on behavioural and physiological correlates of fish stress responses. The effects, and potential benefits, of using analgesia and commercially available water treatments to further refine skin swabbing and aid the recovery of fish from skin damage and stress will also be analysed.



  1. Sneddon, L. (2011). Pain perception in fish. Journal of Consciousness Studies 18(9-10): 209-229.
  2. Lidster K et al. 2017. International survey on the use and welfare of zebrafish Danio rerio in research. Journal of Fish Biology 90(5): 1891-1905. doi: 10.1111/jfb.13278
  3. Breacker C et al. 2017. A Low-cost method of skin swabbing for the collection of DNA samples from small laboratory fish. Zebrafish 14(1): 35-41. doi: 10.1089/zeb.2016.1348


  1. Carreño Gutierrez H et al. (2020). Screening for drugs to reduce zebrafish aggression identifies caffeine and sildenafil. European Neuropsychopharmacology 30:17-29. doi: 10.1016/j.euroneuro.2019.10.005
  2. Tilley CA et al. (2020) Skin swabbing is a refined technique to collect DNA from model fish species. Scientific Reports 10:18212. doi: 10.1038/s41598-020-75304-1
  3. Carreño Gutierrez H et al. (2019). Endothelin neurotransmitter signalling controls zebrafish social behaviour. Scientific Reports 9:3040. doi: 10.1038/s41598-019-39907-7
  4. Norton WHJ and Carreño Gutierrez H (2019). The three-spined stickleback as a model for behavioural neuroscience. PLoS One 14(3): e0213320. doi: 10.1371/journal.pone.0213320