Describe the structure of a fish's heart and explain how blood flows to and from it.

Answer: Fish have a two-chambered heart that pumps blood from the heart to the gills, from the gills to the rest of the body, then back to the heart.

The heart of a fish is known as a branchial heart

Function and structure; it's main structure is to pump Venous blood to ventral aorta into gills (i. e branchial) and then to somatic vasculature. Thus, branchial and systematic vascular beds are arranged in series with heart.

Apart from heart, heart like organs are present in Agnatha (Myxine and petromyzon). The heart of fishes consist of four Chambers a sinous venosus, an atrium, a ventricle and a conus or a bulbus Arteriosus.