3 Stripe Damselfish

The three striped damselfish, scientifically known as Dascyllus aruanus (also commonly called the humbug dascyllus or three stripe dascyllus), is a small marine teleost fish widespread throughout the tropical reefs of the Indo-Pacific region. Reaching an average adult size of 3 to 4 inches (7.5 to 10 centimeters) in length, it is easily recognized by its deep-bodied profile and high-contrast pattern of three bold, vertical black bars alternating with bright white bands across its head and torso. In their natural habitat, these damselfish are tightly bound to branching stony corals, particularly Acropora species, where large groups retreat instantly between the branches when threatened. They are active planktivores that hover just above coral heads during the day to feed on zooplankton, copepods, and micro-crustaceans drifting in the current. Because they are coral-dwelling fish, they are 100% reef-safe and will not pick at stony corals, soft corals, or mobile invertebrates like crustaceans and snails.

In a home aquarium, Dascyllus aruanus is extremely hardy and adaptable to varying water conditions, making it a frequent choice for beginners. However, despite its small size and attractive appearance, it is notoriously aggressive and highly territorial. As it matures, it will fiercely defend its chosen rockwork or coral structure against both peaceful tank mates and larger fish. To minimize hostility, aquarists should introduce it to the tank last or house it alongside larger, equally semi-aggressive species in systems with plenty of visual barriers.