I think my goldfish is dying?

my goldfish (they are like half the size of a baseball) are sitting on the bottom of them tank and breathing hard. One of them is turning white and laying on his side, he tries to move every so often but then just settles back on his side. The other one moves a bit more but it breathing realllyyyy hard, he is siting on his stomach. I took them out of their usual tank because i feared something might be wrong with the water, so theyre now in a new one with fresh water. I love these fish and i want to help them, it there anthing i can do?