Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtainthe best experience, we recommend you use a more up to date browser (or turn off compatibility mode inInternet Explorer). In the meantime, to ensure continued support, we are displaying the site without stylesand JavaScript.AdvertisementInside the mind of an animalYou have full access to this article via your institution.Your browser does not support the audio element.Two years ago, Jennifer Li and Drew Robson were trawling through terabytes of data from a zebrafish-brain experiment...…Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtainthe best experience, we recommend you use a more up to date browser (or turn off compatibility mode inInternet Explorer). In the meantime, to ensure continued support, we are displaying the site without stylesand JavaScript.AdvertisementInside the mind of an animalYou have full access to this article via your institution.Your browser does not support the audio element.Two years ago, Jennifer Li and Drew Robson were trawling through terabytes of data from a zebrafish-brain experiment...WW…