Flowerhorn cichlids are ornamental aquarium fish noted for their vivid colors and the distinctively shaped heads for which they are named. Their head protuberance, or kok, is formally termed a nuchal hump. Like blood parrot cichlids, they are man-made hybrids that exist in the wild only because of their release. Flowerhorns first emerged for sale on the aquarium market in Malaysia in the late 1990s and soon became popular in many countries in Asia. First developed in Malaysia, Thailand, and Taiwan, they became very popular with Asian fish hobbyists. They are also kept by hobbyists in the US, India and Europe. Numerous cast-off flowerhorns have been released to the wild, especially in Singapore and Malaysia, where they have become an invasive pest animal. Their importation is banned in Australia.