Neurotensin (NTS) is a 13 amino acid neuropeptide that is expressed in the hypothalamus. In mammals, NTS-producing neurons that express leptin receptor (LepRb) regulate the function of hypocretin/orexin (HCRT) neurons. Thus, the hypothalamic leptin/NTS/HCRT neuronal network orchestrates key homeostatic output, including sleep, feeding and reward. However, the intricate mechanisms of the circuitry and the unique role of NTS-expressing neurons remain unclear. We studied the NTS neuronal networks in zebrafish and cloned the genes encoding the NTS neuropeptide and receptor (NTSR). Similar to mammals, the ligand is expressed primarily in the hypothalamus, while the receptor is expressed widely throughout the brain. A portion of hypothalamic nts-expressing neurons are inhibitory and some co-express leptin receptor (LepR1). As in mammals, NTS and HCRT neurons are localized adjacently in the hypothalamus. In order to track the development and axonal projection of NTS neurons, a partial NTS promoter sequence was isolated. Transgenesis and double labeling of NTS and HCRT neurons showed that NTS axons project toward HCRT neurons, some of which express ntsr. To determine the genetic, neuroanatomical, and behavioral role of NTS, we generated a CRISPR-based mutant zebrafish line (nts-/-). Using a video-tracking behavioral system, we studied the neurological and behavioral phenotype of the nts-/- fish. These findings suggest structural and functional circuitry between leptin, NTS and hypocretinergic neurons, and establish the zebrafish as a model to study the role of NTS in the regulation of key behavioral states such as feeding, sleep and wake.