Bettas have five fin types pectoral, dorsal, caudal, anal and ventral. In male bettas tall of these fins but the pectorals are usually longer than those of the female. This is most obvious in the common domestic bettas although short finned bettas have fins that are only as long as those of longfin females. This has caused some confusion among many people but the thing to look for is the ovipositor as pictured below.
