Known by multiple common names, such as humbug damselfish, three-striped damselfish and white-tailed damselfish, Dascyllus aruanus is a feisty little fish that adapts well to aquarium life. White-tailed damselfish can be pugnacious and are better introduced at the latter stages of setting up a marine fish community.
Difficulty level: The white-tailed damselfish is tough and forgiving. The white-tailed damselfish is considered a good “starter” fish for anyone entering marine fishkeeping for the first time.
Hardiness: The white-tailed damselfish tolerates a range of water conditions, from passable to pristine. However, it is the responsibility of all aquarists to ensure that their fishes receive the best possible living conditions that can be provided — anything less wouldn’t be fair to these fish.
Physical description: The white-tailed damselfish tops out at about 4 inches in total length. Sporting three broad black stripes on a white body, the white-tailed damselfish has a zebralike appearance. The stripes run slightly off vertical through the eyes and mouth, midbody and bisecting the caudal peduncle, making it half black and half white. The caudal fin is clear, which distinguishes it from the black-tailed damselfish (D. melanurus), which looks nearly identical except for its namesake black caudal fin. Male and female white-tailed damselfish can be virtually the same size and coloration at maturity; however, the sexes can be distinguished through visually examining their respective genital areas.
Climate and range: Dascyllus aruanus ranges throughout much of the Indian and Pacific oceans and in the Red Sea. The white-tailed damselfish does not occur in the Atlantic Basin. The white-tailed damselfish is a tropical reef fish that is most often found in aggregations in the vicinity of branching corals.
Compatibility: The white-tailed damselfish can be quite territorial in aquaria and will aggressively defend. For this reason, the white-tailed damselfish should be stocked after other fish are already established; the white-tailed damselfish should also be kept with other fish of similar size and temperament. Individual white-tailed damselfish should have a cave or branching coral specimen to call its own. You’ll want to make sure that each white-tailed damselfish has enough room, as they will fight among themselves as well as harass other fish. The white-tailed damselfish is considered reef-safe, but it has been reported to nip at hermit crabs and shrimp. If new to the aquarium hobby, I recommend the white-tailed damselfish be kept in an aquarium all to themselves. If you want to establish the white-tailed damselfish as part of a fish community later, purchase another aquarium and introduce it only after the other fish have become established.
Aquarium conditions: While often used to cycle new marine aquarium setups, the white-tailed damselfish still does best when kept in optimal water conditions with slight to medium flow. The water temperature for the white-tailed damselfish should be maintained between 75 and 82 degrees Fahrenheit; another website recommends they be kept in water temperatures of 72 to 78 degrees. Other parameters include pH of 8.1 to 8.4; dKH 8 to 12; specific gravity 1.019 to 1.026.
Care considerations: The white-tailed damselfish can be kept by itself in setups of as little as 10 gallons, but a minimum aquarium size of 30 gallons is recommended. The white-tailed damselfish needs to have plenty of crevices in the rockwork in which to occasionally hide and feel secure. Being diurnal the white-tailed damselfish also uses crevices or small caves in the rockwork to turn in for the night.
The white-tailed damselfish is an omnivore and eats a variety of foods in the wild. A varied diet of meaty frozen foodstuffs, algae-based foods and commercial flake will keep the white-tailed damselfish healthy and active.
Breeding in aquaria: The white-tailed damselfish is among the handful of marine fishes hobbyists have successfully bred, produced and reared offspring from in aquaria. The male white-tailed damselfish cares for the fertilized eggs until the pelagic fry take up residence in the aquarium’s water column. Remove as many of the white-tailed damselfish fry as you want to try and raise to a rearing aquarium, with an absence of adult fish and invertebrates that might look upon the young fish as tasty morsels for the taking. Dascyllus aruanus is a worthy first-time breeding project for up-and-coming marine aquarists.