When buying goldfish, why did the seller say that goldfish should be kept in odd numbers instead of even numbers?

Generally speaking, people who believe in fish numbers in fish tanks like to keep 1, 3, 5, 6, 7, 8, 9, 12, 19, 24, 36, 39, 55, 66, 69, 72, 99. The best numbers are. Generally speaking, the total number of fish is odd.

Goldfish can make the most money, while snakehead can only be raised by people with special occupations (such as soldiers and scholars). Generally speaking, snakehead is easier to attract villains, right or wrong, but it is not conducive to making money. The number of fish farming also varies according to personal life, such as the following: rat, pig: 1 or 6 tigers, rabbit: 3 or 8 snakes, horse: 2 or 7 monkeys, chicken: 4 or 9 or 5.