By Gisela Telis The way to a woman's heart is through her stomach--at least for the swordtail characin. When a male of this tropical freshwater species (Corynopoma riisei) wants to mate, he dangles an "ornament"--a flag-like appendage normally hidden close to his body--in front of his desired date. The ornaments come in different shapes and sizes, and researchers have suspected since the 1960s that the shapes reflect the females' preferred foods.