Three species of hamlets, Hypoplectrus chlorurus, H. unicolor, and H. puella (Pisces: Serranidae) were observed underwater off the west coast of Puerto Rico. They are predaceous fishes, feeding on small benthic organisms, and live in close association with the coral reef. Hamlets are highly aggressive and defend large territories, excluding their own and all other species of hamlets. They are synchronous hermaphrodites. In spawning, which occurs around sunset, one member of the pair ascends, the other joins it, each clasps the nape of the other with its tail, and gametes are released. Little color change occurs, but the black marking before the eye of H. unicolor fades when fixing on prey, proving it is not used as a sighting line. The all-black nominal species H. nigricans spawns with the yellow-tailed H. chlorurus, and is regarded here as a synonym of H. chlorurus.