CART (cocaine- and amphetamine-regulated transcript) peptides are novel brain neuropeptides that have been shown to have a role in the control of feeding behavior in mammals. The effects of intracereboventricular (i.c.v.) administration of two CART fragments, CART (62-76) and CART (55-102) on feeding and behavioral activity of goldfish (Carassius auratus) were examined. Both CART peptide fragments inhibited food intake in goldfish. Co-injection of CART peptide and neuropeptide Y (NPY) reduced the increase in feeding caused by injection of NPY alone. CART (55-102) was more potent than CART (62-76). Co-treatment with CART (55-102) and orexin A inhibited the feeding response induced by orexin A alone. Feeding behavior was stimulated relative to saline controls following injection of CART (62-76) alone and co-injection of NPY and CART (62-76), but was not affected by treatment with CART (55-102) alone, NPY and CART (55-102) or orexin A and CART (55-102). Total behavioral activity was increased with NPY, orexin A, and both CART fragments alone as compared to saline controls, as well as in fish co-treated with NPY and CART (62-76) or NPY and CART (55-102) as compared to saline controls and NPY-treated fish. Tremors were seen in fish treated with CART (55-102) alone, and in fish co-treated with NPY and CART (55-102) and orexin A and CART (55-102). Co-treatment of the fish with NPY but not with orexin A significantly lowered the frequency of fish showing tremors as compared to fish treated with CART alone. These results indicate that CART peptides are involved in the regulatory pathways of feeding and behavioral activity in goldfish.