The zebrafish serves as a model organism for researchers around the world: it can be used to study important physiological processes that also take place in a similar form in the human body. It is therefore routinely used in the search for possible active substances against diseases. Researchers have now described an innovative way to do this. In this process, the larvae fish are made a bit more ‘human-like’. This humanization could make the search for active pharmaceutical substances much more efficient.