Do fish have an incomplete closed circulatory system?

Fish have a single circulatory pattern, wherein the blood passes through the heart only once during each complete circuit. Oxygen-deprived blood from the body tissues comes to the heart, from where it is pumped to the gills. Gaseous exchange happens within the gills, and the oxygenated blood from the gills is circulated throughout the body.

On the other hand, in mammals, the deoxygenated blood enters the heart, from where it is pumped into the lungs for oxygenation. The oxygenated blood returns to the heart from the lungs, to be transported throughout the body.

~Buzzle: