How did the black flame betta come from?

Black flame betta is the red color of black betta. According to the relevant information, the red color of black betta is caused by many pigments, including astaxanthin. The combination of astaxanthin and protein is very unstable. When the fish is not fresh, this combination is decomposed, and astaxanthin also appears, which makes the body color of betta fish change from blue-gray to red.