Can a fish get a cold?
Yes but it can be deadly to the fish if it a sudden change (like changing the tank water) or if the fish isn't supposed to live in cold.
Yes. For example, if you put them in freezer and touch 'em, they are cold.
Yes. Fish survive at a certain water temperature :)
No, because there are cold blooded and there body temperature can vary with the temperature in there Surroundings.
Yes. Like your heart, fish can get really coldHang on. A cold? Like the flu? No, because the rhino virus dies in water.