If you’re planning any kind of change to your pond that involves removing the fish from the pond for an extended period of time, it is best to provide some sort of housing for the fish that causes the least amount of stress on them. What I suggest doing is to take a large Rubbermaid tub or small plastic kid pool to house the fish and fill that up with pond water. Be sure to place this tub in a shaded area and place a net over the pool to keep the fish from jumping out.
Be sure to provide something to aerate the water, I would suggest taking a small water pump and placing that in the pool so that you have plenty of circulation. Don’t feed excessive amounts of food while the fish are in the holding area, limited the food to a small amount and only what they will eat in five minutes. Feed them only once a day as too much food will cause all sorts of health issues. When you are ready to move the fish back to the pond, make sure that the temperatures of the pool and the pond are about the same. If they are, you will want to slowly re-introduce your fish back into the pond.