Dascyllus trimaculatus (Domino Damselfish / Three-Spot Damselfish)
• Small fish safe: ❌ No
• Small invert safe: ✅ Yes
• Coral safe: ✅ Yes
• Minimum tank size: 208 liters (55 gallons) or larger
• Adult size: Up to 14 cm (5.5 inches)
• Diet: Omnivorous (varied diet including algae, planktonic crustaceans, and prepared aquarium foods)
• Be aware of: Highly aggressive and territorial, especially as they mature. Best kept singly or in pairs in appropriately sized tanks with similarly aggressive or larger tank mates. Juveniles are more social but become solitary and dominant as they age.
Domino Damselfish (Dascyllus trimaculatus) – A Striking Yet Aggressive Marine Species
The Domino Damselfish, also known as the Three-Spot Damselfish, is a visually striking species recognized for its distinctive coloration and robust nature. While its hardiness makes it appealing to aquarists, its notoriously aggressive behavior necessitates careful consideration when adding it to a community tank.
Appearance and Coloration
The Domino Damselfish is characterized by:
• Juveniles: Deep black body adorned with three prominent white spots—one on the forehead and one on each side.
• Adults: Coloration may fade to a lighter gray, and the white spots often diminish or disappear entirely.
• Body Shape: Deep-bodied with a laterally compressed form, contributing to its distinctive appearance.
This transformation in coloration as they mature adds to their unique appeal in marine aquariums.
Natural Habitat and Behavior
Native to the Indo-Pacific region, including the Red Sea, Domino Damselfish are typically found in:
• Juveniles: Often associated with sea anemones, forming symbiotic relationships similar to clownfish.
• Adults: Prefer coral-rich areas and lagoon reefs, where they establish and defend territories.
In the wild, juveniles exhibit social behavior, forming groups, while adults become more solitary and highly territorial.
Tank Requirements and Water Parameters
To accommodate the Domino Damselfish’s needs:
• Minimum Tank Size: 208 liters (55 gallons) or larger to provide ample space and reduce territorial aggression.
• Aquascape: Incorporate abundant live rock formations to create hiding spots and establish territories.
• Water Parameters:
• Temperature: 24–27°C (75–81°F)
• pH: 8.1–8.4
• Salinity: Specific gravity of 1.020–1.025
Maintaining stable water conditions with regular monitoring is essential for their health.
Diet and Feeding
Domino Damselfish are omnivorous with a hearty appetite:
• In the Wild: Feed on algae and planktonic crustaceans.
• In Captivity: Accept a variety of foods, including:
• High-quality marine flakes and pellets (preferably vitamin-enriched)
• Frozen or live foods such as mysis shrimp and brine shrimp
• Algae-based foods to supplement their diet
Feeding once or twice daily with a varied diet will help maintain their health and coloration.
Compatibility and Tank Mates
Due to their aggressive and territorial nature, careful selection of tank mates is crucial:
• Suitable Tank Mates: Other aggressive or semi-aggressive species of similar or larger size, such as certain wrasses, tangs, or triggerfish.
• Invertebrates: Generally reef-safe, posing no threat to corals or most invertebrates.
Avoid Housing With:
• Passive or timid fish, which may be harassed or bullied.
• Other damselfish species, unless in a very large tank with ample hiding spots.
If keeping multiple Domino Damselfish, it’s advisable to introduce them simultaneously to minimize territorial disputes.
Breeding and Reproduction
Breeding Domino Damselfish in captivity is possible:
• Spawning: They are substrate spawners, with females depositing adhesive eggs onto flat surfaces such as rocks or aquarium glass.
• Parental Care: Males typically guard and aerate the eggs until they hatch.
Providing flat surfaces and maintaining excellent water quality can encourage breeding behavior.
Health and Disease Considerations
Domino Damselfish are hardy and resilient, but they can be susceptible to common marine diseases if stressed:
• Marine Ich (Cryptocaryon irritans): Can occur under poor water conditions or high stress levels.
• Bacterial Infections: May result from injuries due to aggressive interactions.
To maintain their health:
• Provide a balanced diet with a mix of protein and plant-based foods.
• Ensure stable water conditions with proper filtration and regular maintenance.