Goldfish Circulatory system
The circulatory system of fish is responsible for transporting blood and nutrients throughout the body. Blood travels across the body through the network of blood vessels. Unlike humans, fish have single cycle circulation, where the oxygen-deprived blood comes to the heart, from where it is pumped to the gills and then circulated to the entire body. The circulatory system of fish consists of a heart, blood and blood vessels. The heart of a fish is a simple muscular structure that is located between the posterior gill arches. In most fish, the heart consists of an atrium, a ventricle, a sac-like thin walled structure known as sinus venosus and a tube, known as bulbus arteriosus. In spite of containing four parts, the heart of a fish is considered two-chambered.