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    Chromis and damsels

    Green chromis

    Chromis viridis

    Also sold as Blue-green chromis, Blue-green reef chromis

    Good first fish

    Green chromis (Chromis viridis), photographed in the sea or an aquarium
    Photo: Debra Baker, CC BY 4.0, via Wikimedia Commons
    Care level
    Beginner
    Adult size
    10.2 cm in aquariums
    Minimum tank
    114 litres
    Temperament
    Peaceful
    With corals
    Reef safe
    Captive-bred
    Occasionally captive-bred
    IUCN status
    Least Concern
    Show volumes in

    How do you care for the green chromis?

    Peaceful to other species; pecking-order fights within the group.

    Feeding

    Planktivore/omnivore.

    Several small feeds a day.

    Tank and special needs

    Plan for at least 114 litres of water (the care sheet says 30 US gallons).

    Open swimming space.

    Why this care level

    Easy individually, but groups in small tanks commonly dwindle to one or two as dominant fish kill weaker ones (Aquanerd, retailer guides).

    Corals and invertebrates

    None.

    Which tankmates suit the green chromis?

    Odd-numbered groups of five or more in larger tanks, all added together; or keep one.

    Suggested order in a mixed tank: add early, with the first peaceful fish.

    More than one green chromis

    Best kept as a group added at the same time, in a tank big enough for the group.

    Other fish

    Checked against the other 59 fish in this guide, assuming a tank big enough for both. Individual fish differ, so treat this as a starting point.

    Avoid together (1)

    • Humbug damselHumbug damsel is aggressive and may bully the green chromis, especially if the bully is added first. Humbug damsels have been reported harassing chromis to death.

    Take care (2)

    • Maroon clownfishMaroon clownfish is aggressive and may bully the green chromis, especially if the bully is added first.
    • Powder blue tangPowder blue tang is aggressive and may bully the green chromis, especially if the bully is added first.
    Usually fine together (56)

    Invertebrates

    Only the invertebrates with a known risk are listed.

    Take care (2)

    • Tiger tail sea cucumberA stressed or dead tiger tail sea cucumber can release toxins that harm fish; cover pump intakes.
    • Sea appleA stressed or dead sea apple can release toxins that harm fish; cover pump intakes.

    Corals and anemones

    Only the corals and anemones with a known risk are listed.

    Take care (1)

    These checks follow the reasons fish and invertebrates clash: same species or genus, similar shape, mouth size, temperament, food, burrows, tank size and the order they are added. Individual animals differ; every source agrees on that.

    Quarantine and health

    Prone to velvet and ich in transit; quarantine the group together.

    New fish are the most common way disease gets into a reef tank. Quarantine every fish in a separate tank before it joins the display, and choose a method that suits its tolerance of copper.

    Captive-bred or wild?

    Captive-bred supply exists but most are wild.

    Where sources disagree

    Where sources disagree
    TopicWhat sources sayOur reading
    Group size and tank
    • 30 US gallons for four to six fish.
    • 75 US gallons for a small group; 400 to 500 litres for nine to eleven.
    		Groups fail in small tanks. Keep one fish, or five or more in a large tank, added together.

    Other minimum tank sizes we found:

    • 30 gal for 4 to 6 (Reef Chasers)
    • 75 gal or more for a small group (Top Shelf Aquatics)
    • 400 to 500 L for a true school of 9 to 11 (Singapore retailer guide)

    What does it cost in the UK?

    about £8. This is one UK retailer’s listing on 21 October 2026, not a market average, and every item was sold out on that day.

    Sources

    1. LiveAquaria (US retailer) care sheetRead 21 October 2026, search summary only. Used for: stats.
    2. Aquanerd articleRead 21 October 2026, search summary only. Used for: group dwindling.
    3. Top Shelf Aquatics (US retailer) guideRead 21 October 2026, search summary only. Used for: tank size.
    4. FishBase species summaryRead 21 October 2026, read in full. Used for: max length, IUCN.
    5. Kraken Corals (UK retailer) catalogueRead 21 October 2026, read in full. Used for: UK price.

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    Yellowtail blue damsel

    Chrysiptera parasema

    Good first fish

    Care
    Beginner
    Adult size
    7 cm
    Tank from
    114 litres
    Temperament
    Mostly peaceful
    Corals
    Reef safe

    Photo Brian Ong, CC BY-SA 3.0

    Blue damsel

    Chrysiptera cyanea

    Care
    Beginner
    Adult size
    8 cm
    Tank from
    114 litres
    Temperament
    Semi-aggressive
    Corals
    Reef safe

    Photo Brian Gratwicke, CC BY 2.0

    Azure damsel

    Chrysiptera hemicyanea

    Care
    Beginner
    Adult size
    7 cm
    Tank from
    114 litres
    Temperament
    Semi-aggressive
    Corals
    Reef safe

    Photo Haplochromis, Public domain

    Humbug damsel

    Dascyllus aruanus

    Not for beginners

    Care
    Beginner
    Adult size
    10 cm
    Tank from
    114 litres
    Temperament
    Aggressive
    Corals
    Reef safe

    Photo Rickard Zerpe, CC BY 2.0