<p>This short review appears in a special issue assembled to celebrate the 90th birthday of a Hungarian ethologist, Professor Vilmos Csányi. As such, it includes some autobiographical details specific to that scientist and the author of this review. However, these details also serve an important general message. They exemplify how science, i.e., specifically the use of fish in the analysis of behaviour and brain function progressed from the mid-1970s to the current day. They illuminate how scientists choose their study species, and how this choice influences the research questions one may be able to pose. The review discusses why the zebrafish has become a popular research subject of biology, including behavioural neuroscience. It argues that behavioural analysis should be an integral part of research into the analysis of brain function. It considers the dichotomy between the historical effect of North American behaviourism vs. the legacy of European Nobel laureate ethologists. It demonstrates, through a theoretical example, why merging these two “schools” of thoughts is the appropriate way to conduct behavioural research. It provides a few examples for how combining knowledge of ethology and ecology of the species with systematic laboratory studies may be beneficial. And it presents a brief outlook for the future of fish in biology research.</p>