No matter how much we try to save a goldfish, there comes a time when the fish lives for weeks in constant suffering. When this is so, It is best to humanely dispose of it. The easiest way to dispose a goldfish with a terminal disease is to place it in plastic bag with salt water and put it in the freezer overnight. The addition of salt (2 teaspoons per gallon) lowers the freezing point of the water. Because goldfish are cold blooded, when the temperature decreases so does its awareness, the goldfish will quietly pass away before the water freezes.