Chrysiptera parasema (Yellowtail Damselfish / Yellowtail Blue Damselfish)
• Small fish safe: ✅ Yes
• Small invert safe: ✅ Yes
• Coral safe: ✅ Yes
• Minimum tank size: 75L+ (preferably 100L+ for groups)
• Adult size: ~7 cm (2.8 inches)
• Diet: Omnivorous (marine pellets, frozen mysis/brine shrimp, algae-based foods)
• Be aware of: Less aggressive than other damselfish, but still territorial, especially as adults. Best kept in small groups in larger tanks to disperse aggression. Juveniles are peaceful, but adults may become more dominant over tank mates.
Yellowtail Damselfish (Chrysiptera parasema) – A Hardy and Colorful Beginner Fish
The Yellowtail Damselfish, also known as the Yellowtail Blue Damselfish, is a stunning yet hardy reef fish that is widely popular among both beginner and experienced aquarists. Unlike some other damselfish, this species is less aggressive, making it a great choice for community tanks. Its brilliant blue body and bright yellow tail add a vibrant pop of color to marine aquariums.
Appearance and Coloration
The Yellowtail Damselfish is one of the most visually striking damselfish, featuring:
• A deep, electric blue body, which remains vivid under most lighting conditions.
• A bright yellow tail, which sharply contrasts with the blue body.
• Rounded fins and a compact, oval-shaped body, giving it a strong, sturdy build.
• A small adult size (~7 cm / 2.8 inches), making it suitable for smaller reef tanks.
Unlike other damselfish, Chrysiptera parasema does not develop dark markings with age, maintaining its brilliant colors throughout its life.
Natural Habitat and Behaviour
Native to the Indo-Pacific, including Indonesia, the Philippines, and the Great Barrier Reef, Yellowtail Damselfish inhabit shallow reef lagoons and rocky coastal areas, where they:
• Live in small groups near coral or rocky formations for shelter.
• Establish small territories, defending them against similar-sized fish.
• Are more social than other damselfish species, showing less aggression in community tanks.
• Dart in and out of rockwork, adding lively movement to the tank.
In captivity, they retain their active and curious nature, making them a fun and engaging species to observe.
Tank Requirements and Water Parameters
Due to their territorial but manageable aggression, Yellowtail Damselfish require a well-structured aquarium with plenty of hiding places.
• Minimum tank size: 75L+ (100L+ recommended for groups or community tanks)
• Temperature: 24–27°C (75–81°F)
• pH: 8.1–8.4
• Salinity: 1.020–1.025
• Water movement: Moderate to strong
• Filtration: Good filtration and regular water changes to maintain stable water conditions.
A tank with plenty of caves, rock formations, and coral structures provides natural shelter, reducing stress and aggression.
Diet and Feeding
Yellowtail Damselfish are omnivorous and require a balanced diet for vibrant coloration and overall health.
Recommended foods include:
• Frozen mysis and brine shrimp – Provides protein.
• High-quality marine pellets and flakes – Look for color-enhancing formulas.
• Algae-based foods and spirulina – Supports digestion and coloration.
• Finely chopped seafood (shrimp, squid, or fish) – Occasional protein treats.
Feed once or twice daily, ensuring a mix of protein and plant-based foods to maintain their color and energy levels.
Compatibility and Tank Mates
Yellowtail Damselfish are one of the least aggressive damselfish, making them easier to keep in community tanks.
✔ Peaceful and semi-aggressive tank mates, such as Clownfish, Wrasses, Tangs, and Blennies.
✔ Larger, non-aggressive fish, which can hold their own against minor damselfish aggression.
✔ Reef-safe invertebrates, including shrimp, snails, and crabs.
Avoid housing with:
❌ Highly aggressive fish, such as large Dottybacks or aggressive Triggerfish.
❌ More aggressive damselfish species, as they may become territorial toward their own kind.
❌ Very small, delicate fish, which may be harassed.
⚠ If keeping multiple Yellowtail Damselfish, introduce them simultaneously and provide ample hiding spots to reduce aggression.
Behavior and Territoriality
Unlike more aggressive damselfish, Yellowtail Damselfish:
• Tend to be more peaceful, especially when provided with enough space.
• Will defend a small territory, but are not as aggressive as species like the Blue Damselfish (Chrysiptera cyanea).
• Are active swimmers, constantly exploring their surroundings.
⚠ If kept in a small tank, they may become more territorial. Keeping them in larger aquariums with good hiding spots helps prevent aggression.
Health and Disease Considerations
Yellowtail Damselfish are extremely hardy, but they can be vulnerable to:
• Marine Ich (Cryptocaryon irritans) – Often caused by stress or poor water quality.
• Bacterial infections – Can occur from territorial disputes or injuries.
• Nutritional deficiencies – A varied diet helps prevent color fading and immune issues.
To keep them healthy:
✔ Provide a balanced diet with a mix of protein and plant-based foods.
✔ Ensure stable water conditions with proper filtration.
✔ Quarantine new fish before introducing them to the main tank.
Lifespan and Long-Term Care
With proper care, Yellowtail Damselfish can live up to 5-6 years in captivity. Their resilient nature, bold personality, and striking coloration make them a great addition to well-planned reef tanks.
Why Choose a Yellowtail Damselfish?
✔ One of the most colorful and peaceful damselfish, perfect for reef tanks.
✔ Hardy and beginner-friendly, adapting well to various conditions.
✔ More community-friendly than other damselfish, making them easier to house with other fish.
✔ Completely reef-safe, with no risk to corals or invertebrates.
✔ Long lifespan, making them a great long-term addition to aquariums.
⚠ Important Considerations Before Buying a Yellowtail Damselfish:
🚫 Can still be territorial, especially in small tanks or without hiding places.
🚫 May become dominant over very passive fish, so tank mate selection is important.
🚫 Best introduced in groups if keeping multiples, to prevent a single dominant individual.