okay I got it backward for the clown, but what I said is true for other fish:
protandry
An example of protandry is found in the anemonefishes. The fishes live with anemones in a symbiotic relationship; the anemone provide the fish with shelter and protection from predation, and the fish supply the anemone with food. Groups of fishes will live with one anemone, and will not switch anemones. Only the two largest will mate; the largest female and the second largest, the male. With the female being the largest, she can produce the most eggs. When the female dies, the largest male will change sexes and become the female. The rest of the fish are immature males.
protogyny
A classic example of protogyny is found in the wrasses and parrotfishes. The males in these species form harems, with one large male sequestering and defending a group of smaller females. The male enjoys spectacular reproductive success, as it has many females to mate with. The females also enjoy a limited reproductive success, producing as many eggs as they can, all fertilized by the one male. The male has the advantage over the females; it has many females producing eggs for him to fertilize, whereas the females only have themselves. It is great to be the king!
Care of:
http://www.marinebiology.org/fish.htm