Domino Damsel (Dascyllus trimaculatus): Ultimate Care Guide


The Domino Damsel is a hardy tank inhabitant with striking coloration. When juvenile, they are black with a white spot on the forehead and white spots on either side. This spot pattern gives them alternative name of Three Spot Damsel. When mature these spots mostly disappear, leaving adults with a solid body color ranging from light to dark gray. This is a great species for beginning aquarium hobbyists as it’s an eager eater that’s tolerant of a range of aquarium water parameters. But this isn’t the best fish for everyone: it can be aggressive to tank mates, especially when spawning. It’s often kept in an aquarium by itself or with species it won’t attack such as Corals or Anemones. When kept with Anemones it will sometimes choose one as its territory, nestling between the tentacles like a Clownfish

Looking to add this fish to your collection? Starting out in the aquarium hobby? We’ve put together this guide with all the information you’ll need to have success with this popular and tough marine fish!

Are Domino Damsel Reef Safe?

While Domino Damsels can fight with other fish, particularly as they age, they won’t harm corals or invertebrates which makes them reef safe. That said, they can become bullies as they mature and do best with larger fish who are already established in the aquarium. Domino Damsels are territorial, and this is made worse if they are an early tank addition. It’s best to add this fish when it’s young, and after larger fish have already claimed territory.

Domino Damsel (Dascyllus trimaculatus)
Domino Damsel (Dascyllus trimaculatus)

Domino Damsel Care

Tough and hardy, the Domino Damsel is an easy beginner’s fish with simple care needs. It can be aggressive, so any tank mates must be chosen with care. This fish can exist in a range of tank sizes and configurations making it a good fit for many aquarium setups.

Are Domino Damsel easy to care for?

Domino Damsel are easy to feed and care for. They are eager eaters who will bite on almost anything that is offered. They’re also tough: they can handle water parameter swings better than many other marine species. This makes it easier to keep them in smaller aquariums which are more susceptible to rapid water quality swings. Because of this, Domino Damsels are a great beginner’s saltwater fish.

Temperature

Domino Damsels prefer water temperatures between 72° and 78° F.

Water pH

Like many reef tank species, Domino Damsels need water pH between 8.1 and 8.4.

Domino Damsel Size

Domino Damsels will only reach a maximum size of 5 ½ inches, making them slightly larger than Clownfish.

Food & Diet

Domino Damsels are omnivores which need a varied diet of prepared pellet and flake food along with algae wafers. In a mature aquarium, this fish will forage for additional food on their own. Domino Damsels aren’t picky eaters, and will eat a wide range of foods. They are also aggressive feeders and will be among the first fishes in your tank to bite on newly added food. In fact, they are so aggressive that you’ll need to make sure other tank mates are getting enough food. It’s better to feed this fish multiple smaller meals each day, but don’t feed more than they can consume within five minutes.

Domino Damsel (Dascyllus trimaculatus)
Domino Damsel (Dascyllus trimaculatus)

Lifespan

A long-lived fish, Domino Damsels can survive up to 20 years in an aquarium.

Tank Size

Domino Damsels need a tank size of at least 55 gallons. Only include one per tank unless it’s a large tank of at least 75 gallons. This is an aggressive species which can be kept alone in a separate aquarium.

Tank Setup

Domino Damsels are hardy fish that tolerate a wide range of tank setups. They can be paired with Anemones and may decide to nestle inside its tentacles like a Clownfish. Anemones are much more sensitive to water quality than Domino Damsels, and their requirements will take priority if you choose to include one or more. Having a mature tank with live rock is a good idea, as this fish can forage for food in addition to their regular feedings. A mature aquarium isn’t a requirement as this hardy fish isn’t sensitive to water quality swings, and doesn’t have to forage for food. They also do well in smaller tanks which can experience more water quality fluctuations than larger tanks which have more water volume to buffer and prevent sudden changes.

Tank aquascaping comes down to personal preference and the needs of any tank mates. Domino Damsels aren’t particular about substrate choice: sand and crushed coral are both acceptable choices. While reef safe for corals, Domino Damsels are a more aggressive species which can bully other fish. If you decide to keep this fish with other tank mates, the other fish need caves and hardscape hiding spaces where they can claim territory far away from the Domino Damsel.

Breeding

Domino Damsel breeding is possible but not common. It’s important to have a mated pair, but this is difficult as sex is hard to determine from outside appearances. If you have a mated pair, this fish spawns similarly to Clownfish with a mating dance over a smooth rock with final egg laying and fertilization. Domino Damsels can become extremely aggressive when caring for eggs or young fry. During this phase they will attack other tank inhabitants or anything which disturbs their environment.

Feeding fry will also be a challenge. Like Clownfish, Domino Damsel fry are tiny and need a diet of small foods like rotifers, specifically Brachionus Plicatilis. Rotifers need phytoplankton for food. Phytoplankton, also known as “Green Water,” is a type of algae, and must be cultured to feed the rotifers, which can then be fed to young Domino Damsel fry. If this sounds like a lot of work, it is. Feeding is only one of the challenging aspects to raising Domino Damsel fry. If you decide to breed this fish it will require a lot of planning and preparation. Breeding Domino Damsel fish is a task best suited to the advanced aquarium hobbyist or commercial breeders.

Disease

Domino Damsels are hardy but can become infected with a range of saltwater diseases: Marine Ich, Marine Velvet, and Uronema. These conditions are treatable with medications but can wreak havoc in a large display aquarium containing a collection of different species. Medications which can cure one fish may kill another. Some species can carry infections without becoming infected themselves, making inclusive tank-wide treatments difficult. Ideally any fish destined for a community aquarium should spend 6 to 8 weeks in a quarantine tank (QT). Time in a QT gives you a chance to catch signs of infection before moving fish to a heavily populated aquarium. Disease signs can include: white spots, blotches, bloating, or unusual swimming patterns. A QT is often smaller and doesn’t contain any elements that can’t be disposed of or sanitized. Should treatment be necessary, this can be given in the QT to only the infected fish. For instance, an infected Domino Damsel in a QT could be treated with medicine that would kill coral. But once cured, they can be moved to a community aquarium with corals and other tank mates.

Are Domino Damsel Aggressive?

Domino Damsel can be aggressive, and this tendency increases with age. During spawning, aggression becomes a problem, and attacks on tank mates are common. You can try to reduce these tendencies by introducing Domino Damsels to your tank while they’re still young. If this species grows up in a tank where larger fish have already staked out territory they are less likely to decide that everything belongs to them. But even this is no guarantee, and a mature Domino Damsel can be a threat to many different marine tank inhabitants. When attempting to mix with other tank mates they must be watched closely for signs of violence and separated if necessary.

Tank Mates

Choosing tank mates for a Domino Damsel can be a challenge because they can be aggressive. Safe species include: LPS and SPS Corals, Sea Fans, Anemones, Shrimp, Crabs, and Snails. Any species that doesn’t look and act like a competitor fish is often a safe bet. Avoid slow and timid tank mates like Seahorses, Gobies, Dartfish, and Fairy Wrasses. Domino Damsels are too aggressive and will attack these fish. Clownfish should be avoided as they can come under attack from an aggressive Domino. There are some species that are aggressive enough to hold their own against Domino Damsels without being a lethal threat. Some of these are: Tangs, large Angels, and large Wrasses. But as tough as Domino Damsels are, there are some even bigger bullies which should be avoided such as Lionfish and Six Lined Soapfish. Choosing the right tank mates for this species is tricky and sometimes it is best to give them their own aquarium where they can’t bully other fish.

Where can I find Domino Damsel for sale?

Domino Damsels are readily available from local fish stores and online sellers. Expect to pay from $10 USD to $20 USD per fish, depending on size.

Fish Laboratory

With decades of collective fishkeeping experience, we are happy to share the fish care tips that we've picked up along the way. Our goal at Fish Laboratory is to keep publishing accurate content to help fishkeepers keep their fish and aquarium healthy.

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