How many chambers are there in the heart of a fish?

The heart in fish is located on the side of the abdomen, just behind the gills. Unlike the human heart, it is two-chambered. Unfortunately, such a structure of the heart does not imply warm-bloodedness, that is, fish are cold-blooded animals.
The heart in fish consists of the atrium, ventricle and aortic bulb, as well as two valves connecting the atrium to the ventricle and the ventricle to the aortic bulb.
The blood from their heart goes directly into the abdominal aorta, and the venous blood flows through the Cuvier ducts into the venous sinus and from there into the heart.