Thomas712 - your answer was perfect and right on the money. All clownfish start out as males. The strongest and most dominiate male wins the opportunity to become a female. Once they convert to a female, or if the male fish has grown past the juevie phase, they will remain male.
Buy two of the same kind of Clownfish and buy them young and small. You will wind up with a mated pair. Better yet, get them from the same tank so the 2 fish already know each other.