Fish have a simple circulatory system, which consists of a two-chambered heart, blood, and blood vessels.
The circulatory system of fish is a closed circulatory system, in which blood is always contained in a circuit of blood vessels.
Fish have a single systemic circuit in which the heart pumps the blood to the gills to be re-oxygenated (gill circulation), after which the blood flows to the rest of the body and back to the heart.
