Description
Bicolour Chromis (Pycnochromis margaritifer)
Overview
The Bicolour Chromis is a hardy and active damselfish known for its simple yet striking appearance—typically dark brown to black on the front half of the body with a contrasting white to pale rear half. Growing to about 7–8 cm (3 inches), it is smaller than many damselfish and less aggressive, making it one of the more peaceful species in the group. Its schooling nature and adaptability make it a popular choice for reef and community marine aquariums.
Origin
Found across the Indo-Pacific region, including the Red Sea, Indian Ocean, and Pacific reefs around Fiji, the Philippines, and Indonesia. It inhabits shallow reef slopes and lagoons, often among branching corals where it can dart for cover.
Feeding
The Bicolour Chromis is an omnivore with a strong preference for planktonic foods. In aquariums, it thrives on a mixed diet of:
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High-quality marine flakes and micro-pellets
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Frozen foods such as mysis shrimp, cyclops, and brine shrimp
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Occasional finely chopped seafood
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Algae-based foods or spirulina for balance
Feed 2–3 small meals daily for best colour and energy.
Tank Mates
Generally peaceful, especially compared to other damselfish. Suitable companions include:
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Clownfish
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Gobies and blennies
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Wrasses (reef-safe species)
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Cardinalfish
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Other small, peaceful reef fish
They may also school with other chromis species, though mixing different types sometimes causes chasing. Avoid very aggressive or much larger predatory fish.
Aggression
Peaceful to semi-aggressive. While usually mild-mannered, they can become territorial if kept singly or in cramped conditions. Best results are achieved in small groups (5–7 individuals) in a suitably sized tank.
Experience Level
Beginner-friendly. Hardy, adaptable, and easy to feed, the Bicolour Chromis is a good introduction to marine keeping and reef aquariums.
Water Parameters
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Temperature: 23–27°C (73–81°F)
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pH: 8.1–8.4
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Salinity: 1.020–1.025 SG
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Hardness (dKH): 8–12
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Tank Size: Minimum 30 gallons (115L) for a small group; larger tanks allow for more natural schooling behaviour
Provide branching rockwork or corals for cover and open swimming space.
Reef Compatibility
Reef safe. Will not harm corals or invertebrates, making them excellent additions to reef tanks.
