Final answer:
Blood enters the ventricle and is pumped to the gills for gas exchange in fish. This is called gill circulation.
Step-by-step explanation:
The true statement about blood circulation in fish is that blood enters the ventricle and then is pumped to the gills where gas exchange occurs and the blood is re-oxygenated. This is called gill circulation. The blood then continues through the rest of the body before returning to the atrium, completing the systemic circulation.