1. Reason: Parrot fish may be frightened because of their black body. Although they are fierce in character, their courage is relatively small. When cultured artificially, if there is a loud noise around or someone slaps the fish tank hard, they will be frightened.

2. Treatment: The blackening of parrot fish after being frightened belongs to stress reaction, so the breeder only needs to ensure that the surrounding environment is quiet. After the parrot fish recovers from the frightened mood, the black will naturally disappear.

1. Reason: The blackening of parrot fish may be caused by too much environmental change, such as too large temperature difference between morning and evening, too large amount of water change, and great change of water quality between new water and old water. All these changes will stimulate parrot fish, causing them to turn black.

2. Treatment: The breeder needs to keep the surrounding environment stable, the water temperature should be controlled between 25-28 ℃, and the PH value should be kept between 5.5-7.0. When changing water at ordinary times, we should pay attention to the amount and frequency of changing water to keep the environment stable.

1. Reason: The blackening of parrot fish may also be affected by genes, and they are crossed by red devil fish and purple red fire mouth fish. Purple red fire mouth fish will have black spots on their bodies, so parrot fish with some genetic mutations will also have black spots on their bodies.

2. Treatment: This condition does not need deliberate treatment, because the black spots will disappear after they reach adulthood, so the breeder does not need treatment.