The pretty Three Stripe Damsel is one of the few damselfish that keeps its stripes for life!
The Three Stripe Damsel Dascyllus aruanus is an attractive black and white striped fish with a white nose and white tail. Unlike many fancy damselfish youths that become unspectacular, even drab, as adults, this handsome fellow retains it’s juvenile coloring into adulthood. There are no bland adults here, although they may become a bit more muted as they mature. They have many common names, but are also popularly known as the Humbug Dascyllus, White Tailed Damselfish, and Black and White Damselfish.
A group makes a spectacular display in the aquarium when they have rockwork or coral to hover around. This is because in the ocean they will often live in a commensal relationship with corals. Interestingly, they have also been known to defend their coral from the Crown of Thorns Starfish!
With their dramatic color pattern they are highly sought after damselfish. They usually only grow to about 2 1/2 inches and may live up to 15 years in captivity. Along with that, their durability and low cost makes them suitable for beginners. The problem with the Three Stripe Damsels however, is that as they get older they retain their good looks, but they don’t retain the calmer attitude.
They are adorable and sweet as juveniles, swimming in large groups together. They are easy to keep, however, their peaceful schooling behavior changes with age in a captive environment. They are aggressive as adults and tank mates need to be carefully chosen. Their aggression becomes disastrous for community type tank mates and they may protest any attempt to add other fish once they are established.
A male and female pair may be kept together, otherwise only keep one per tank with no other damselfish. Tank mates need to be aggressive or larger semi-aggressive fish. Any peaceful and smaller semi-aggressive fish will be attacked. Do not house them with fish that can swallow them whole. That being said, you may want to pass on predatory fish too, since Dascyllus have the ability to visually identify predators and may not come out to feed.
Provide a tank that is at least 30 gallons for one damselfish, along with rockwork and/or coral that offers nooks and crannies for them to retreat. Providing many places for them to hide as juveniles will help them adjust. They are omnivores and appreciate algae in the tank. Any substrate, water movement, or lighting is acceptable. As juveniles they will swim in the upper levels of the aquarium in schools, though adults may inhabit any level if they do not have a host branching coral.
For more Information on keeping saltwater fish see:
Marine Aquarium Basics: Guide to a Healthy Saltwater Aquarium
- Kingdom: Animalia
- Phylum: Chordata
- Family: Pomacentridae
- Genus: Dascyllus
- Species: aruanus
- Aquarist Experience Level: Beginner
- Aquarium Hardiness: Very Hardy
- Minimum Tank Size: 30 gal (114 L)
- Size of fish – inches: 3.9 inches (10.01 cm)
- Temperament: Aggressive
- Temperature: 72.0 to 82.0° F (22.2 to 27.8° C)
- Range ph: 8.1-8.4
- Diet Type: Omnivore
- My Aquarium – Enter your aquarium to see if this fish is compatible!
Habitat: Distribution / Background
The Three Stripe Damsel Dascyllus aruanus was described by Linnaeus in 1758. They are found in the Indo-Pacific from the Red Sea and East Africa to the Marquesan Island, Tuamoto Island and Pitcairn Island. They are also found from southern Japan and southward to Sydney, Australia. This species is not listed on the IUCN Red List of Threatened Species.
There are more common names and many of them relate to their black and white stripes. These include Humbug Damsel, Humbug Dascyllus, Humbug Damselfish, Common Humbug, Banded Humbug, White-tailed Damselfish, White Tailed Dascyllus, Black and White Damselfish, White Tailed Footballer, and Zebra Humbug.
About the Dascyllus Genus:
This species is a member of the very large Pomacentridae family of Damselfish and Anemonefish. It belongs to the subfamily Chrominae in the Dascyllus genus. There are currently 10 recognized species in this genus and they are only found in the Indo-Pacific.
The Dascyllus species are very deep bodied damselfish. They have a commensal relationship with corals and are often found hovering around isolated coral heads in groups. These groups range in size depending on the size of the coral. Once a Dascyllus has located a home at a coral colony it remains there.
They hide within the coral colony when frightened and use it as protection at night. In turn, the coral colony benefits from the fish waste and water movement they produce between their branches. In fact, studies have shown those corals with groups of Dascyllus grow faster and larger than those without. These damsels have the ability to visually tell the difference between a nearby herbivore and a predator, by the placement of the eyes and the shape of the mouth.
The largest dominant fish in a group is always male, but when the dominant male is removed the largest female then transforms into the dominant male. With some species there may be several females in the process of becoming male even while subordinate. Many Dascyllus, including this species, are known to be hermaphrodites, starting life as female and turning male on demand. Yet it is also thought that there are some species that are gonochorists, where they are born as either male or female.
Similar to clownfish, this genus produces sounds to communicate. They make at least three distinct pulse sounds, and the larger the specimen the lower the frequency. Chirps and pops are audible with some species when the males are engaged in fighting, during courting, and when caring for and defending eggs in the nest site.
Of all the damselfish species only two (possibly three) from the Dascyllus genus are known to associate with anemones. These are the Domino Damsel Dascyllus trimaculatus, the Hawaiian Dascyllus Dascyllus albisella, and possibly the Strasburg’s Dascyllus Dascyllus strasburgi. Unlike their Clownfish relatives they are only found with anemones as juveniles, so are considered “facultative symbionts.” Clownfish, on the other hand, live with anemones their entire lives so are known as “obligate symbionts.”
Dascyllus are very attractive as juveniles, exhibiting dynamic color patterns. As juveniles they can be kept in a group, but as they age they become extremely territorial and mean in the confined space of the aquarium. They will be aggressive with their own kind and other damsels, as well as other fish that are not equally boisterous and pugnacious.
About Three Stripe Dascyllus:
The Three Stripe Damselfish inhabit sub-tidal reef flats, shallow lagoons, reef faces, and fore reef slopes at depths of 3.3 to 39 feet (1 to 12 m). They forms groups of 3 up to 25 fish. Smaller schooling groups are found over isolated coral heads that are at least 3 feet in diameter. The larger schools, with up to 25 members, live above large thickets coral that consist of branching small polyped stony (SPS) coral varieties.
The corals they choose in the wild seem to match up with their maturity. While juveniles prefer thinner branching coral species like Pocillopora and Stylophora, adults prefer coarsely branched or lobed branching corals like Acropora. These fish will not venture more than 3 feet (1 m) away from their corals and will quickly hide within the coral colony when frightened and use it as protection at night. They have also been known to defend their coral from the Crown of Thorns Starfish.
Three Stripe Damsels, unlike some in their genus, feed heavily on filamentous algae, algal fronds, fish eggs, larvae, and various planktonic crustaceans. These include Galatheid Crabs (a small white hairy crabs that are in the lobster family), copepods, polychaetes, Tanaids (small skinny stretched out shrimp that are 5 mm long), insects, fish scales and cumaceans (small crustacean that looks like a flea with a scorpion’s tail, though they are only .04” or 1 to 10 mm long).
- Scientific Name: Dascyllus aruanus
- Social Grouping: Groups – Adults are generally found in small to large groups, between 3 to 25 individuals.
- IUCN Red List: NE – Not Evaluated or not listed
The Three Stripe Damsel is a deep bodied fish that’s not built for speed as well as other damselfish, so they tend to stay closer to their host coral. Some interactions such as being engaged in fighting, or when courting or caring for their nest, may result in these fish producing distinct pulsing sounds.
They can reach up to 3 3/4 inches (10 cm) in length, though typically only grow to about 2 1/3 inches in the aquarium. Males are larger than females. In the wild their life span is about 6 years, though they may live up to 15 years in captivity.
They have a white body with three black vertical black stripes, a white nose, and a white tail. The first black stripe runs across the eye, the second is slightly curved back and in line with the pelvic fin, and the third is at the back end of the body. The pectoral fins are clear and the pelvic fins are black. The coloration is the same for juveniles and adults, though they may become more muted as they age.
Another Dascyllus species that is similar in appearance to the Three Stripe Damsel is the Four Striped Damsel, Dascyllus melanurus. The Four Striped has three stripes on the body just like the Three Stripe Damsel, but has another black stripe or spot on the end of the tail fin.
- Size of fish – inches: 3.9 inches (10.01 cm) – They typically only grow to about 2 1/3 inches (6 cm) in length in the aquarium.
- Lifespan: 15 years – These damselfish generally live up to 6 years in the wild and up to 15 in captivity.
Fish Keeping Difficulty
The Three-Stripe Damselfish are generally among the easiest marine fish to keep. They are very hardy and relatively small, making them suitable for a beginning saltwater hobbyist. They are gregarious as juveniles and can be kept in a group, but they become very aggressive as they age, so tankmates should be chosen with care.
The only things they really need are a few places to hide in rockwork and to be fed 3 times a day. Even though they are quite durable they still can fall ill if exposed to poor water conditions for too long. Doing normal water changes, feeding them a variety of foods several times a day, and having proper tank mates are important when keeping this damselfish.
- Aquarium Hardiness: Very Hardy
- Aquarist Experience Level: Beginner – They are suitable for a beginner, but tankmates must be selected with care.
Foods and Feeding
Three-Stripe Damselfish are omnivores. In the wild they feed heavily on algae but also consume fish eggs, larvae, and various planktonic crustaceans. In the aquarium provide variety in their diet that includes mysis, enriched brine shrimp, krill, finely chopped shrimp, fish flesh and other meaty foods, as well as flakes and preparations for herbivores.. If there is no algae in the tank, then a little flake food for herbivores can be given.
They need to be fed twice a day, though less if there is a lot of algae in the tank. If feeding pellets, make sure they are wet before adding them to the tank so air will not get into their digestive tract, which can cause issues.
- Diet Type: Omnivore – Flakes and pellets should have spirulina for added nutrition.
- Flake Food: Yes
- Tablet / Pellet: Yes – Make sure the pellets are wetted down with tank water before adding to prevent air from getting trapped in their digestive tract.
- Live foods (fishes, shrimps, worms): Some of Diet – Not really necessary unless trying to condition a pair to spawn.
- Vegetable Food: Half of Diet
- Meaty Food: Half of Diet
- Feeding Frequency: Several feedings per day – Feed 2 times a day, and less if there is an abundance of edible algae.
These damselfish are hardy and easy to keep with a well maintained tank. Regular water changes done bi-weekly will also help replace the trace elements that the fish and corals use up. Guidelines for water changes with different types and sizes of aquariums are:
- Fish only tanks:
- Nano/Small tanks up to 40 gallons, perform 5% water changes bi-weekly.
- Medium sized up to 90 gallons, perform 15% bi-weekly.
- Large Tanks 100 gallons and over, once water is aged and stable, can be changed 10% bi-weekly to 20% monthly, depending on bioload.
- Reef tanks:
- Nano/Small tanks up to 40 gallons, perform 15% water changes bi-weekly.
- Medium sized up to 90 gallons, perform 20% to 30% monthly depending on bioload.
- Large Tanks 100 gallons and over, once water is aged and stable, can be changed 20% to 30% every 6 weeks depending on bioload.
For more information on maintaining a saltwater aquarium see: Saltwater Aquarium Basics: Maintenance. A reef tank will require specialized filtration and lighting equipment. Learn more about reef keeping see: Mini Reef Aquarium Basics.
- Water Changes: Bi-weekly – Do bi-weekly water changes of 15% in a reef setting or 20% monthly in a fish only tank.
The Three-Stripe Damsel can be kept in either a saltwater aquarium or a mini reef. They only get to around 3 inches but they are very deep bodied and round, so need plenty of room to get around. They will swim in the upper levels of the aquarium in schools as juveniles. Adults may inhabit any level if they do not have a branching coral to hover above and retreat in for shelter.
A tank that is at least 30 gallons is best for one damsel. If keeping a male and female pair provide at least 55 gallons, adding more damsels will require an even larger tank. If you want to keep it other damsels, having one damsel per 50 gallons is advised.They become aggressive as they get older, so other tank mates should be chosen wisely.
Provide a decor of rocks and/or coral to create plenty of hiding places. Live rock with various hiding places, or even branching small polyped stony (SPS) corals, are ideal. Having many places to hide will reduce aggression between them and other fish in the tank. Any substrate, water movement, and lighting is fine unless housed with corals, then these factors need to be considered for the needs of the coral. The normal water temperature should be between 72˚F to 82˚F (22 – 28˚C), with pH from 8.1 to 8.4. Similar to clownfish, optimal spawning production occurs between 79°F to 83°F (26°C to 28°C).
- Minimum Tank Size: 30 gal (114 L) – A 30 gallon tank is suggested for one specimen, 55 gallons or more for a pair.
- Suitable for Nano Tank: No
- Live Rock Requirement: Typical Plus Hiding Places
- Substrate Type: Any
- Lighting Needs: Any – It has no special lighting requirements, though stronger lighting will promote much appreciated algae growth. If kept with live coral, it may need strong lighting.
- Temperature: 72.0 to 82.0° F (22.2 to 27.8° C)
- Breeding Temperature: 79.0° F – The optimal temperature for good quality eggs and larvae occurs with temperatures of 79° F to 82° F (26° – 28°C).
- Specific gravity: 1.023-1.025 SG
- Range ph: 8.1-8.4
- Brackish: No
- Water Movement: Any
- Water Region: All – Juveniles tend to stay near the top, but adults will stay close to a host coral if present.
Three Stripe Damsels are aggressive, though compared to some damsels like the Fiji Blue Devil DamselfishChrysiptera taupou, they are not so bad. They are fine as juveniles, either in a school or alone, but as they grow older, their attitude grows and more belligerent. It is best to keep just one per tank, unless it is a male/female pair, or the tank is large with plenty of hiding places. Once paired they are even more aggressive than when alone.
Tank mates need to be other fish as aggressive as they are, or much larger. Peaceful and smaller semi-aggressive fish will be attacked as this fish ages, to the point where the damselfish takes over an entire community tank. If attempting to keep with smaller semi-aggressive fish like dwarf angelfish, the tank should be at least 100 gallons with plenty of hiding place for the other fish.
In tanks under 100 gallons, ideally try to house with triggerfish, large angelfish, butterflyfish, larger dottybacks or other species that can hold their own with aggressive fish. Do not house with fish who can swallow them whole. It may be wise to avoid housing with any predatory fish, even if they are not big enough to eat the Three Stripe Damsel. This is because of these damsels ability to recognize a predator, which may keep them from coming out and eating.
They will work great in a reef and really pose no threat. Their presence can actually benefit branching small polyp stony (SPS) corals. Invertebrates are generally safe though small crustaceans like copepods, amphipods, and others may be eaten. Only if the tank is very large with a huge colony of established copepods, will they not be depleted. Be cautious with small ornamental shrimps, like the Sexy Anemone Shrimp Thor amboinensis, as they may be attacked.
- Venomous: No
- Temperament: Aggressive
- Compatible with:
- Same species – conspecifics: Sometimes – A male/female pair will need 75 gallons or more, with plenty of places for retreat in the rockwork.
- Peaceful fish (gobies, dartfish, assessors, fairy wrasses): Threat – Three Stripe Damsels are too aggressive for these fish.
- Semi-Aggressive (anthias, clownfish, dwarf angels): Monitor – Three Stripe Damsels are too aggressive for these fish unless housed in a tank that is at least 100 gallons or more
- Monitor – Six-line or Eight-line wrasses may be picked on, depending on the individual damsel and the tank size.
- Large Semi-Aggressive (tangs, large angels, large wrasses): Safe
- Large Aggressive, Predatory (lionfish, groupers, soapfish): Threat – Even a smaller predatory fish that cannot swallow them whole would make these damselfish too afraid to come out and feed.
- Threat – Three Stripe Damsels are too aggressive for these fish.
- Anemones: Safe
- Mushroom Anemones – Corallimorphs: Safe
- LPS corals: Safe
- SPS corals: Safe – These damsels are beneficial for branching small polyped stony (SPS) corals.
- Gorgonians, Sea Fans: Safe
- Leather Corals: Safe
- Soft Corals (xenias, tree corals): Safe
- Star Polyps, Organ Pipe Coral: Safe
- Zoanthids – Button Polyps, Sea Mats: Safe
- Sponges, Tunicates: Safe
- Shrimps, Crabs, Snails: Monitor – Be cautious about adding small ornamental shrimp, like sexy shrimp, as they may become dinner.
- Starfish: Safe
- Feather Dusters, Bristle Worms, Flatworms: Safe
- Clams, Scallops, Oysters: Safe
- Copepods, Amphipods, Mini Brittle Stars: Monitor – Copepod and amphipod populations should be well established in a larger tank, or they can easily be diminished by the Three Stripe Damsel.
Sex: Sexual differences
Three Stripe Damsel males are larger and are the dominant fish in the group or pair. They are also all born female and some dominant females may have slightly undeveloped male organs to allow them to quickly turn into a male if the dominant male disappears.
Breeding / Reproduction
The Three Stripe Damselfish have been bred in captivity, following the general pattern of clownfish. If breeding in captivity, note that brittle stars, serpent stars, wrasses and crabs will eat the eggs of damselfish. The eggs and larvae are much smaller than clownfish, and are difficult to rear.
Spawning was also observed 2 to 4 days around the new and full moon in the reefs around Sesoko Island, Okinawa. Spawning was done early in the morning during the months of June to September. They may spawn more often in warmer waters. There is a pecking order in which the alpha female spawns with the alpha male first, then other females will spawn next in descending order. Males may even try to spawn with females in group nearby if that other male is small.
Successful breeding requires perfect water parameters and a large, non-predatory aquarium system. Three Stripe Damsels, opposite of clownfish, are born female and change to male as they move up the hierarchy. Similar to clownfish, optimal spawns are between 79°F to 83°F (26°C to 28°C). In typical Dascyllus genus fashion, the male chooses a spawning site which can be a rock, dead coral branch, coral rubble, or flat rock.
To attract a female, the male will engage in signal jumping and will produce sounds. Signal jumping is the behavior of dipping up and down quickly. Once the female sees that the male is ready to spawn, she will join him. They will then swim side by side, with the male slightly behind the female. Then both turn almost completely white, vibrate, and then simultaneously deposit their gametes on the nesting site.
After the eggs are laid and fertilized, the male produces more even more pulse sounds as he defends the nest. One clutch can have over 1,000 eggs. The male will oxygenate the eggs and remove any that are undeveloped. He will viciously guard his nest until they hatch. The eggs will hatch in 2 to 2.5 days, right after sunset, and then the larval stage lasts for 20 to 28 day. Due to similarities, see breeding techniques under Clownfish on the Marine Fish Breeding page.
- Ease of Breeding: Difficult – The eggs and larvae of damselfish are quite small and the fry are difficult to rear.
Dascyllus are very durable damsels, even when juveniles. However there does seem to be an unexplained “sudden death” that damselfish can occasionally fall victim to. There are no signs, the fish is just dead one day. They can contract any normal disease that other saltwater fish are susceptible to. But it is pretty rare unless they are captured with an illness already in motion, so a quarantine period is a good idea.
Damselfish are susceptible to Marine Ich Cryptocaryon irritans, also called White Spot Disease or Crypt, Marine Velvet or Velvet Disease Oodinium ocellatum (Syns: Amyloodinium ocellatum, Branchiophilus maris), and Uronema disease Uronema marinum. All of these are parasites.
The most easily cured of these is Crypt (salt water Ich), but they are all treatable if caught in a timely manner. Marine Velvet is a parasitic skin flagellate and one of the most common maladies experienced in the marine aquarium. It is a fast moving that primarily it infects the gills. Uronema disease, which is typically a secondary infection, is very deadly and will attack your Chromis quickly and lethally.The first symptom is lack of appetite. It is most often contracted when the aquarist lowers the salinity to treat another type of illness, but doesn’t lower it far enough. This parasite thrives in mid-level brackish water salinity, which is a specific gravity of around 1.013 to 1.020.
Treat your new damselfish as gingerly as you would an expensive saltwater fish, and they will respond well. Anything you add to your tank that has not been properly cleaned or quarantined, including live rock, corals and fish can introduce disease. The best prevention is to properly clean or quarantine anything you want to add to the tank. For information about saltwater fish diseases and illnesses, see Aquarium Fish Diseases and Treatments.
The Three Stripe Damselfish are inexpensive and readily available from pet stores and online.
- Animal-World References: Marine and Reef
- Dascyllus aruanus (Linnaeus, 1758) Whitetail dascyllus, Fishbase
- Scott W. Michael , Damselfishes & Anemonefishes, TFH Publications, 2008
- Scott W. Michael, The 101 Best Saltwater Fishes, TFH Publications, 2007
- Scott W. Michael, Reef Aquarium Fishes: 500+ Essential-to-Know Species, Microcosm Ltd, 2006
- H. Debelius and R. H. Kuiter, World Atlas of Marine Fishes, (in German) Hollywood Import & Export, Inc., 2006
- Dr. Gerald R. Allen, Damselfishes Of The World, Aquarium Systems, 1991
- Burgess, Axelrod, Hunziker III, Dr. Burgess’s Atlas of Marine Aquarium Fishes, T.F.H Publications inc., 1990