How do bony fish regulate temperature?
Since most fish are bony this would count for all cold-blooded fish (minus cartilaginous ones such as the shark or sting ray). Because fish are cold-blooded or exothermic they change body temperature according to the water temperature. In order to regulate their temperature they either move to warmer or colder water, or they change the blood flow to blood vessels near the surface of there skin or fins and use this to change the rate in which they change color. Since the colder the water the slower the animal (in the case of cold blooded animals) many fish live in warmer waters, but there are still fish that live as far up as the arctic or as far down as the coast of Antarctica .