Are Blue Green Chromis reef-safe?

Yes, Blue Green Chromis are generally considered reef-safe. They do not normally damage corals or prey on ornamental reef invertebrates. Their peaceful nature and midwater schooling behavior make them ideal for adding movement and color to reef systems.

What tank mates are compatible with Blue Green Chromis?

Blue Green Chromis are peaceful and compatible with a wide range of reef-safe species, including clownfish (Ocellaris, Percula), gobies, firefish, wrasses, tangs, and blennies. Avoid housing them with large predatory fish or highly aggressive species that may bully or prey on them. Also exercise caution with territorial damselfish and aggressive clownfish species (e.g., Maroon, Tomato) which may harass them.

How long do Blue Green Chromis live?

Reliable captive lifespan data for Blue Green Chromis is limited. Aquarium specimens are often reported to live several years under good conditions, but published long-term captive longevity figures are inconsistent. With appropriate care, they can live for several years, but a well-established species-specific captive lifespan range is not available.

Are Blue Green Chromis aggressive?

Blue Green Chromis are one of the most peaceful damselfish species. However, within a school, a dominance hierarchy can develop, and dominant individuals may harass subordinates. This aggression is typically diffused in larger groups (10+ individuals) and spacious tanks. They are not aggressive toward other species.

What is the maximum size of Blue Green Chromis?

The maximum documented total length for Blue Green Chromis is approximately 10 cm (4 inches). In aquariums, they typically reach 5–6 cm (2–2.5 inches) standard length.

Blue Green Chromis (Chromis viridis)

Saltwaterpeacefulbeginner Care

Quick Answer

Blue Green Chromis (Chromis viridis) should ideally be kept in groups of 6 or more in a 55-gallon or larger aquarium. They are peaceful, reef-safe planktivores that prefer stable reef parameters (pH 8.1–8.4, temp 72–80°F, SG 1.020–1.026) and a varied diet. They are one of the few peaceful damselfish and make excellent community fish.

Max Size 4 in (10 cm)

Difficulty beginner

Diet Planktivore

Quick Facts

Scientific Name	Chromis viridis
Common Names	Blue Green Chromis
Type	Saltwater
Temperament	peaceful
Care Difficulty	beginner
Maximum Size	Up to 4 in (10 cm)
Diet	Planktivore
Temperature	72–80°F (22–27°C)
pH	8.1–8.4
Minimum Size	55 gallons

Key Takeaways

Peaceful temperament, unusual among damselfish.
Recommended: 55+ gallons for a school of 6 or more.
Best kept in groups of 6 or more to reduce stress and promote natural behavior.
Reef-safe and compatible with most peaceful species.

Essential Resources

Beginner Aquarium Setup

Learn how to build the perfect first tank.

Water Chemistry

Keep parameters stable and safe.

Nitrogen Cycle

Understanding the aquarium cycle.

Health

Marine Ich (Cryptocaryon irritans)

A common parasitic infection causing white spots on the skin and gills.

Symptoms

White spots (1–2 mm) on body, fins, and gills; rapid breathing; scratching against objects; lethargy.

Causes

Stress, poor water quality, introduction of infected fish.

Prevention & Treatment

Quarantine new arrivals; maintain stable water parameters; minimize stress.

Marine Velvet (Amyloodinium ocellatum)

A highly contagious parasitic infection that can be rapidly fatal.

Symptoms

Fine golden-brown dust on skin, clamped fins, rapid breathing, loss of appetite, hiding.

Causes

Stress, sudden temperature fluctuations, introduction of carriers.

Prevention & Treatment

Strict quarantine; maintain optimal water quality; avoid overcrowding.

Flukes (Monogenean trematodes)

Flatworm parasites that attach to skin and gills, causing irritation.

Symptoms

Excessive mucus, scratching, flashing, labored breathing, pale gills.

Causes

Introduction of infected fish; poor hygiene.

Prevention & Treatment

Quarantine and prophylactic treatment (e.g., praziquantel) for new arrivals.

Breeding

Blue Green Chromis are substrate spawners. The male prepares a nest site on sand, rubble, or dead coral and courts females with an elaborate swimming display. Several females may deposit eggs in a single male’s nest; each spawning event can produce several thousand eggs (reported ranges vary widely). The male guards and aerates the eggs, removing unfertilized ones. Eggs hatch in approximately 2–3 days at around 27°C (81°F). The larvae are planktonic and require specialized care, including rotifers and phytoplankton. While spawning occurs regularly in captivity, successfully rearing larvae to settlement is challenging and requires dedicated effort.

Compatible Tank Mates

African Butterflyfish

Fair Match

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African Cichlid

Fair Match

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African Leaf Fish

Fair Match

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African Red Eyed Tetra

Fair Match

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Angelfish

Fair Match

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Apistogramma

Fair Match

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African Butterflyfish

Fair Match

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African Cichlid

Fair Match

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African Leaf Fish

Fair Match

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African Red Eyed Tetra

Fair Match

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Angelfish

Fair Match

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Apistogramma

Fair Match

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Species Comparison

Species	Adult Size	Temperament	Minimum Tank Size	Diet	Social Behavior
Blue Green Chromis (Chromis viridis)	10 cm (4 in) TL	Peaceful	55 gal (208 L) for school; 30 gal for single	Planktivore	Schooling
Black Axil Chromis (Chromis atripectoralis)	12 cm (4.7 in) TL	Peaceful	75 gal (284 L) for school; 40 gal for single	Planktivore	Schooling
Blue Chromis (Chromis cyanea)	15 cm (6 in) TL	Peaceful	90 gal (341 L) for school; 55 gal for single	Planktivore	Schooling

Frequently Asked Questions

What is the minimum tank size for Blue Green Chromis?

For a natural social group of 6 or more, a minimum tank size of 55 gallons (208 L) is strongly recommended, with a footprint of at least 36 inches in length. A single specimen may be physically housed in a 30-gallon (114 L) aquarium, but solitary housing does not provide normal schooling behavior and is not recommended as a long-term solution. For groups of 10 or more, consider 75 gallons or larger to diffuse aggression effectively.

What are the ideal water parameters for Blue Green Chromis?

Stable parameters are more important than exact numbers. Recommended ranges: temperature 72–80°F (22–27°C), pH 8.1–8.4, specific gravity 1.020–1.026 (with stability within 0.002), and alkalinity 8–12 dKH. These are typical reef aquarium targets; the species is adaptable if changes are gradual. Ammonia and nitrite must be undetectable; nitrates should be kept below 10 ppm in reef systems.

How many Blue Green Chromis should be kept together?

Blue Green Chromis are naturally schooling and should be kept in groups of 6 or more to encourage natural behavior and reduce stress. Groups of 10 or more are ideal for diffusing the dominance hierarchy that can lead to attrition of weaker individuals. Keeping 2–5 individuals is not recommended, as this often leads to chronic aggression and losses. In tanks under 30 gallons, a single specimen is physically possible, but it will not display schooling behavior and may not thrive long-term.

What do Blue Green Chromis eat?

Blue Green Chromis are planktivorous omnivores. In the wild, they feed primarily on phytoplankton and zooplankton. In captivity, they readily accept high-quality marine flakes, pellets, frozen mysis shrimp, enriched brine shrimp, cyclops, and finely chopped seafood. For optimal health and coloration, include foods enriched with astaxanthin and Spirulina. Feed small amounts multiple times daily (2–3 times) to mimic their natural grazing behavior.