Why does the mouth and body of God of Wealth turn black?

Water temperature, water quality, and newcomers will turn black when they are scared. In addition, the smallest individual who makes a fortune is also prone to black spots. This is not a problem. It's best to eat well with water, and it won't take much time to get better.

It is native to the Amazon River in South America, but it is also found in Vietnam, Thailand and Malaysia in Southeast Asia. Adult fish belonging to the family Percidae are 20-69 cm long, oval, with a big head, a big mouth and a strong physique. The ventral fin is two slender silk fins, the gluteal fin is wide and the pectoral fin is developed. The dorsal fin is low in front and straight in back; The gluteal fin extends from the posterior abdomen to the caudal stalk; The anal fin and caudal fin are golden yellow. The whole body is golden yellow, the eyes are golden yellow, and the scales on the body surface are slightly red and have a metallic luster. In the light, the whole body exudes golden light and resplendent.