New test environment shows unknown sides of zebrafish

Zebrafish are playing an increasingly important role in science

Photograph: Matton

With a new test environment for zebrafish, researchers at Uppsala University and SLU have developed a sophisticated tool for mapping multiple behavioral variables in a single test situation. Now the group presents its first results.

Zebrafish have long been a common sight in our aquariums. Originally native to Asia's tropical freshwater, it has become popular all over the world with its easy care. Recently, it has also swum into laboratories, and is today the second most common vertebrate in scientific studies. Thus, novel tools are needed to utilise its full potential, and in short researchers at Uppsala University and the Swedish University of Agricultural Sciences (SLU) will launch a new test environment that enables effective mapping of individual fish's behavioral profile.

"In collaboration with Svante Winberg, professor of Behavioral Neuroendocrinology, we started out with the model Bengt Meyerson created for rodent studies and applied it to zebrafish. The environment we are now introducing is an aquarium with specially designed zones, enabling researchers to use infrared radiation in order to determine how each fish acts in the face of potential risks and its drive to investigate unknown environments, which is relevant data in behavioral research," says Erika Roman, professor of Domestic Animal Physiology.

The zebrafish has a number of characteristics that make it attractive to researchers: adjustable genetics, rapid development - already two days after conception it has a heart, brain and seeing eyes - and smooth absorption of substances in the water. That it is also very easy to handle entails low overheads - the experiments will be considerably cheaper than performed on mice - and with the new test environment, science will have access to a practical and sophisticated tool that opens up for complex studies in a number of disciplines.

"Already while developing our model, we made several interesting observations. We saw, among many things, that the zebrafish caught in the wild in India explored all zones for the same length of time, while zebrafish born in laboratories for several generations mainly stayed in a few zones, and that gender differences are considerably greater in the laboratory-grown group. We could also state that the fish behave the same during their second visit to the test environment, which is a great advantage compared to the classic behavioral tests," says Laura Vossen, postdoc at SLU.

The group aims to publish the results in 2021 and will at the same time present drawings that will enable other research teams to construct identical test environments. Early demonstrations of the model have aroused great interest and Erika Roman believes that the material will be of great relevance to researchers in domains such as ecology, toxicology, genetics, drug development and the field of addiction.

"Zebrafish continue to play an increasingly important role in science. And the more advanced tools we develop that help us analyse their behavior, the more we will learn. Our model requires further validation, but the fact that it enables the mapping of multiple behavioral variables in a single test situation makes me convinced that we have created a significant complement to traditional preclinical tools."

Magnus Alsne