Researchers used zebrafish to study the effects of knocking out three clock genes, Cry1a, Cry2a, and Per2. They compared wild-type zebrafish with those with single, double, or triple knockout of these genes under conditions of complete darkness, three hours of light, and finally 12 hours of light reflecting typical daylight. The team revealed reduced locomotion and more resting associated with gene knockout, linking this to impaired metabolism.