It must be painful to be the biggest clownfish in the shoal.
You need to get a pair if you want to breed clownfish and you need to sex the fish. And that’s a quite an interesting part – believe it or not, clownfish are all born as males! When they are adults, the largest and the most dominant fish of the group will undergo a sex change, and become a female. The second largest usually becomes the breeding male, while all the other fish remains juveniles and gender-neutral. If the breeding female disappears, the breeding male will change to a female, and so on.
Clownfish are sequential hermaphrodites, meaning that they develop into males first, and when they mature, they become females. If the female clownfish is removed from the group, such as by death, one of the largest and most dominant males will become a female. The remaining males will move up a rank in the hierarchy.