Pomacentrids, or generally better known as Damselfishes and Clownfishes (Pomacentridae) are a family of fish belonging to the order Perciformes. They are predominantly marine fish, although certain species can inhabit brackish water and those in fresh water are very rare. They inhabit tropical seas, and we highlight the Indo-Pacific where there is the greatest diversity and quantity of fish of this family. Etymologically, the scientific name of the family (Pomacentridae) comes from two Greek words. On the one hand 'poma' which refers to the operculum, and on the other 'kentron' which means sawn, referring to the serrated edge of the operculum in many of the species of this family. Damselfishes and Clownfishes live predominantly in surface waters between 2 and 15 metres deep, although some species can live at greater depths.
The body of Damselfishes and Clownfishes is generally tall and laterally compressed. They have a terminal mouth that is small in size. Their lateral line is incomplete or interrupted. Many species have a very vivid coloration and with very varied colors, among which yellow, red, orange and blue predominate. The coloration and its patterns are a serious difficulty when it comes to identifying these species, since many species present complex color patterns that vary between individuals and/or between the different locations where the species is found. Damselfishes and Clownfishes are highly territorial, usually living in relatively small and very specific areas of water, such as a branch of a coral or anemone. In the latter case, the relationship of mutualism allows the fish to stay safe under the shelter of the stinging tentacles of the anemones, while the anemone improves the flow of water and oxygenation of its tentacles. In relation to size, the Damselfishes and Clownfishes do not exceed 35 cm in length.
Damselfishes and Clownfishes have a unique and continuous dorsal fin, formed by 8-17 spines and between 11 and 18 radii. The spiny portion of the dorsal fin is always longer than the portion with spokes. The anal fin is formed by 2 spines, and in a few species 3.
As a curious fact of the Damselfishes and Clownfishes, the care of the clutch falls on the male in many species, who will shake the clutch with some slight movements of his pectoral fins to improve the oxygenation of the eggs. This family of fish is omnivorous, feeding on Algae, plankton and small Crustaceans. Many of the species of this family of fishes known today have been discovered in the last two decades. There are 387 registered species, which are organized into 29 genera, grouped into 4 subfamilies.