1. Reason: Goldfish may suffer from black spot because of black spot, and there are many reasons for goldfish suffering from black spot. For example, trauma, bacterial infection and parasitic infection are all possible.

2. Solution: If the black spot of goldfish is not serious, the breeder only spills 250 grams of crude salt and 250 grams of baking soda in the fish tank. If the black spot is serious, the breeder needs to soak the fish with malachite green solution or methyl blue once a day for 20 minutes each time.

1. Reason: Goldfish's long black spots may also be caused by being frightened. They are timid and easy to be frightened. When the shock is serious, the color of the body will change.

2. Solution: Breeders need to keep their surroundings quiet so that they can recover quickly. During the recovery period, breeders need to keep the environment stable.

1. Reason: The long black spots of goldfish may also be caused by illness, and common diseases will cause the body color change of goldfish. Especially when the disease is serious, the color change will be more obvious.

2, Solution: Breeders need symptomatic treatment according to their diseases, and after they recover, their body color will gradually recover.