Dr. Zohar Ben-Moshe from the Yoav Gothilf Lab identified 14 light-entrained molecular clock genes in the zebrafish system using messenger RNA sequencing and microarray analysis. In this study (Nucleic Acids Research, 2014), genes dec1 and per2 were tested further and found to be essential for the light entrainment of the rhythmic locomotor activity of larvae.
The activity of larvae (dec1 knockdown, per2 knockdown, and control groups) was monitored in a DanioVision system. To entrain rhythms of locomotor activity, 5dpf larvae were exposed to 3 hours of light, after which they were monitored under dim light conditions.
The total distance moved per 10 minute time-bin was automatically measured with EthoVision XT and used to determine the activity level of the larvae. Knockdown of both dec1 and per2 genes resulted in a noticeably disrupted circadian locomotor activity pattern.
Ben-Moshe, Z.; Alon, S.; Mracek, P.; Faigenbloom, L.; Tovin, A.; Vatine, G.D.; Eisenberg, E.; Foulkes, N.S.; Gothilf, Y. (2014). The light-induced transcriptome of the zebrafish pineal gland reveals complex regulation of the circadian clockwork by light. Nucleic Acids Research, 42, 3750-3767.
Read about more studies on circadian rhythmicity in zebrafish in this other case about casein kinase and rhythmicity.