Damselfishes are members of the "Family Pomacentridae" consisting of 4 subfamilies, 28 genera, and 321 species are abundant throughout the world's warm waters. Most available Damselfishes belong to one of the following genera: Abudefduf, Dascyllus, Chromis, Chrysiptera, Paraglyphidon, Pomacentrus, and Stegastes. They have a variety of lifestyles including algae farmers, zooplankton feeders, some of them are partners with sea anemones. Many are highly territorial and may become quite aggressive among themselves and toward other tankmates, males may maintain a harem of females. Most of these fish stay in small shoals in the wild when young, breaking away from the group as they grow, and eventually become solitary as adults.Many species are brilliantly coloured, often in shades of red, orange, yellow, or blue; most do not exceed a length of about 15 cm. Juveniles often have a different coloration from adults. No significant markings or distinguishing characteristics differentiate males from females. Some species (e.g. Cromis) are schooling and peaceful fishes, and basically an open water feeder. Most damselfishes live along reefs, but certain species are noted for living among the stinging tentacles of sea anemones.When dealing with several Damsels in one aquarium, plenty of rockwork and hiding places are necessary in order to keep quarrels to a minimum.