How is blood circulation in fish?

Fish have 1 circle of blood circulation. The heart consists of 2 chambers: the atrium and the ventricle, and there is only venous blood in it. Blood circulation begins in the ventricle of the heart, from where the blood flows through the branchial artery into the gills, where gas exchange occurs in the capillaries: carbon dioxide is removed from the blood, and oxygen enters. From there, arterial blood moves to all organs and tissues, where, in the process of gas exchange, it again becomes venous. From the organs, blood is collected in the veins and flows into the atrium of the heart, and then passes into the ventricle.