Pomacentrids, commonly known as damselfishes and anemonefishes, are one of the most abundant and widely-studied families of tropical reef fishes. Small and brightly colored, they are popular aquarium fish. The family Pomacentridae consists of approximately 28 genera and 335 species. They tend to be territorial and can be aggressive, although this is not the case for the non-territorial, free-swimming planktivores or the anemonefishes (Amphiprion and Premnas) that live commensally with anemone hosts. Damselfishes are largely herbivorous, sometimes tending “gardens” of filamentous algae, but may eat tiny invertebrates, or in the case of anemonefishes, anemones and other organisms living symbiotically with anemones. Damselfishes manifest a range of reproductive behaviors, with groups that are polygynous, promiscuous, polyandrous, and monogamous. Anemonefishes are able to change from male to female under certain conditions (see Reproduction: Mating Systems).