damselfish

Damselfish are small to medium-sized marine fishes in the family Pomacentridae, a diverse group that includes more than 100 species. They are common on tropical reefs and inshore habitats around the world, especially in the Indo-Pacific, with several species also present in the western Atlantic. Damselfish are among the most recognizable reef fishes because of their bright colors, compact bodies, and often bold behavior.

Most damselfish range from about 5 to 20 centimeters in length. They have laterally compressed bodies, rounded fins, and a variety of color patterns that can be sexually dimorphic, particularly during breeding. Many species are territorial as adults, defending feeding zones or nesting sites from intruders and sometimes forming persistent pairs or small groups.

Ecologically, damselfish occupy a range of niches. Some are herbivores that graze on algae, helping shape algal communities on reefs; others are omnivorous or planktivorous, feeding on zooplankton and small invertebrates. Juveniles may form schools, while adults often exhibit strong territorial behavior. Reproduction typically involves spawning between a male and female, with eggs laid on a prepared substrate and the male guarding and aerating the developing eggs until they hatch. In many species, parental care is predominantly provided by the male.

Damselfish play important roles in reef ecosystems as both grazers and prey for larger predators. They are also popular in the ornamental aquarium trade, valued for color but known for their often aggressive behavior in confined spaces and their need for stable, spacious set-ups. Conservation status varies by species; reef degradation and collection pressures threaten some populations, while others remain widespread and abundant.