3 Minute 3Rs April 2021

You’re listening to the April episode of 3 Minute 3Rs.

The papers behind the pod:

1.       Identification of individual zebrafish (Danio rerio): a refined protocol for VIE tagging whist considering animal welfare and the principles of the 3RS. Animals  11, 616 (2021) https://doi.org/10.3390/ani11030616

2.      Enrichment for laboratory zebrafish – a review of the evidence and challenges. Animals 11, 698 (2021) https://doi.org/10.3390/ani11030698

3.      Research relevant background lesions and conditions: ferrets, dogs, swine, sheep, and goats. ILAR J ilab005 (2021) https://doi.org/10.1093/ilar/ilab005

4.      *Bonus* Research-relevant background lesions and conditions in common avian and aquatic species. ILAR J ilab008 (2021) https://doi.org/10.1093/ilar/ilab008


It’s the 3rd Thursday of April and you’re listening to 3 Minute 3Rs, your monthly recap of efforts to replace, reduce, and refine the use of animals in research. This month we’ve got some zebrafish refinements, plus a refresher on some basics for a bunch of different animals. But first, ID please.


If you’ve got a tank full of fish that look identical, how do you make sure you can tell them apart? The zebrafish research community have tried various tagging methods, but until now there hasn’t been a refined and standardized method that can be used on a large scale.

In a new paper in Animals, Anita Rácz and colleagues describe such a method for tagging zebrafish using visible implant elastomer, or VIE. This method is widely used for marking large fish and other aquatic organisms and involves injecting a small amount of coloured elastomer under the fish’s skin.

As well as explaining their refined protocol, including appropriate anaesthesia and analgesia, Rácz and colleagues compare it to a previous protocol and show that it offers significant welfare improvements, including a ten-fold reduction in mortality following the tagging procedure. With zebrafish being used in thousands of labs around the world, particularly in genetic research, this work is bound to make a big splash.


While we’re thinking about zebrafish, have you thought about their tanks look like lately?


Zebrafish have rapidly become one of the most common research animal species with over 5 million fish used worldwide. Currently, most of these fish are housed in barren tanks with no environmental enrichment.

But in a recent review in Animals, the RSPCA Science Department describes current evidence supporting zebrafish enrichment. Its provision improves zebrafish welfare, behavior, and physiology, which can lead to better science. 

One well-supported and fairly easily implemented enrichment is using an image of gravel on the bottom of tanks. The paper also discuss evidence for social housing, plastic plants, live food, and more. To learn more about the current evidence for zebrafish enrichment, read the full paper online.


[LA] And finally, a double feature. A lot of different animals turn up in research labs beyond rodents. But regardless of what species you are using, you need to know what’s normal and what’s not for a given animal in order to accurately interpret any experimental results.  How well do you know an animals’ anatomy and how it differs from the humans they are intended to model? Is that lesion intentional, or a spontaneous...

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