What temperature should you set your water heater to?

from my knowledge of fishkeeping i believe you should go with about 70 on the thermometer not 70 degrees, 70 degrees Fahrenheit. if you were to do 70 degrees the fish would automatically die because the human skin average heat is 35 degrees so can you imagine how harsh that woyld be on the fish skin because the fish sking isn't half as tough as the humans.

other information:

ONLY PUT A HEATER IN TROPICAL FISH TANKS. COLDWATER FISH DONT NEED IT.