1. Reason: Goldfish may be congested because there are too many harmful substances in the water. If there are more harmful substances in the fish tank, goldfish will be easily stimulated, resulting in congestion.

2. Solution: The breeder needs to change the water for goldfish first to ensure that their water quality is clean. Add some coarse salt to avoid wound infection. During their recovery, breeders need to change water every day to avoid deterioration of water quality.

1. Reason: The congestion of goldfish may also be caused by too large a temperature difference. When the temperature in the fish tank changes too much, they will be stimulated, which will also lead to congestion of the fish body.

2. Solution: Breeders need to install a heating rod to keep the water temperature in a stable range. As long as the water temperature is constant, their congestion can be alleviated.

1. Reason: Goldfish is congested all over and may be caused by congestive disease, mainly because goldfish have parasites and bacteria on their bodies.

2. Solution: The breeder needs to clean up the parasites on the goldfish first. If there is decay or infection, the breeder should first give them a potassium permanganate medicated bath, and finally give them a medicated bath with malachite green solution. During the medicated bath, the breeder needs to change the water every day to keep the water quality clean.