According to geomantic omen, red fish can prosper, but extremes meet, so a black fish is needed to resolve evil.
Eight reds and one black are true, but this is a saying. Moreover, from the perspective of feng shui fish, the sweeper does not belong to feng shui fish and cannot be counted. There are koi fish, goldfish, arowana, parrots and so on, and there are also eight fish and one turtle.