Why did the black goldfish turn brown and then recently went from brown to gold?

Upstairs a few people are either talking out of their asses or plagiarizing theories. The black goldfish in the adult goldfish is very little, can adult to maintain the black are very good, which is the reason why the ink dragon price is high. Because the black goldfish is the most unstable, most of the small black fish have become red fish. This is a genetic problem, the growing environment plays a very small factor. -Hidden Dragon Pavilion Aquarium sincerely for your answer