A fish has a heart, which acts as the center of its circulatory system, pumping blood throughout the body and transporting vital nutrients and oxygen to cells. The size, placement and strength of a fish's heart differs b... More »

Fish oil has been studied extensively for reducing coronary heart disease, whereas few studies focus on Krill oil for heart health, according to University of Massachusetts Medical School. Fish oil studies indicate its a... More »

www.reference.com Health Conditions & Diseases Cardiac Health

A fish breathes through its gills, extracting oxygen from the water. Other sea animals, such as whales, breathe oxygen from the air because they are mammals. More »

While there are areas of Lake Erie known as dead zones, where there is not enough oxygen for fish to survive, the lake still contains a wide variety of fish. The location of the fish changes based on a number of factors ... More »

www.reference.com Pets & Animals Marine Life Fish

Gills work in fish in much the same way as lungs do in mammals, as they help take oxygen into the blood and release carbon dioxide. Fish draw water into their mouths, which then travels past the many tiny blood vessels i... More »

www.reference.com Pets & Animals Marine Life Fish

When a lake freezes, fish survive by changing their metabolism, which lessens the amount of food and oxygen that they need. Without this adaptation, fish would not survive the icy winters. More »

Betta fish can breathe oxygen both from the water through their gills and directly from the air above the surface of their bowls for small periods of time. The fish can live for a short period of time in oxygen-deficient... More »