Emergency treatment methods for a goldfish that is full:

1. Change the water. Replace all the goldfish's water with new water. The goldfish will excrete it quickly when it sees the new water. As long as it is discovered in time and replaced with new water, it will be fine in 2 hours.

2. Stop eating. Stop feeding immediately and remove the remaining food from the fish tank to prevent the goldfish from continuing to eat.

3. Promote sports. Stir the water in the fish tank slightly to allow the goldfish to exercise more and help digestion, but not too vigorously to prevent the goldfish from being frightened.

4. Provide oxygen. Use an air pump to inflate the water to increase the amount of dissolved oxygen in the water, speed up the metabolism of the fish, and promote the digestion and defecation of the fish.

5. Increase the water temperature. Raising the water temperature in the fish tank can strengthen the fish's metabolism, and the fish will become active immediately, which can help its digestion.

Methods to prevent goldfish from overeating:

1. Feed in moderation. Breeders should follow the principle of eating small amounts and frequent meals, and provide them with an appropriate amount of food every day.

2. Soak the bait. It is best to soak the prepared bait in water for three to five seconds before feeding it to them to prevent the feed from swelling in the water and making them full.