FISHIES! I NEEED HELP!?

first of all if they are common goldfish they a lot of room because they can get up to a foot long. the cold is not a problem because goldfish are coldwater fish and like the cold better than warmth. get a thermometer for your tank. the water should be around 60 degrees. if you plan on having multiple goldfishes you should be ready to buy a very big tank, some people even say that common goldfish shouldn't be in tanks but in ponds.