Fish obtain energy and nutrients through feeding activities, and appetite is an important factor affecting fish feeding. Appetite regulation is a complex network in which the brain integrates the body's energy and feeding signals to regulate fish feeding behavior through appetite regulators, including orexigenic peptides and anorexigenic peptides. As a new endocrine factor, apelin plays a wide range of biological roles in vivo. Among them, the role of apelin in the regulation of food intake is attracting the attention of researchers. This paper reviews the tissue distribution of apelin, the effects of starvation and nutrients on apelin expression, the effects of apelin treatment on animal feeding, especially fish feeding, its possible mechanisms and signaling pathways, so as to provide references for promoting fish feeding and aquaculture.