Diadema Dottyback (Pictichromis diadema)
The Diadema Dottyback, also known as the Purplestripe Dottyback, is a small but incredibly striking fish that packs a lot of "attitude" into a tiny package. It is a favorite for nano reefs due to its neon-bright colors, but it carries a reputation for being one of the feistiest fish in the marine hobby.
Key Information
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Common Names: Diadema Dottyback, Purplestripe Dottyback, Diadem Pseudochromis
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Scientific Name: Pictichromis diadema
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Origin: Western Pacific (Philippines, Indonesia, Malaysia)
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Max Size: 6 cm (approx. 2.5 inches)
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Lifespan: 5–7 years
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Temperament: Aggressive; highly territorial and bold
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Diet: Carnivore – Loves meaty frozen foods and small crustaceans
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Care Level: Easy
Appearance & Identification
The Diadema is easily identified by its "royal" color scheme:
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Primary Color: A vivid, bright yellow body.
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The "Diadem": A distinct magenta-to-purple stripe that runs along the dorsal ridge (the "crown") from the snout to the base of the tail.
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Eyes: Features large, dark eyes that give it an alert, inquisitive expression.
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Form: It has an elongated, torpedo-shaped body built for darting in and out of tight crevices.
Behaviour & Tank Compatibility
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The "Lurker": This fish spends its time "patrolling" the rockwork. It rarely swims in open water, preferring to hop from one cave to another.
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Aggression: Do not let its size fool you. It is extremely territorial. It will often harass fish much larger than itself if they come too close to its favorite cave.
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Invertebrate Risk: It is a natural predator of small ornamental shrimp. It may pick at Peppermint Shrimp or Sexy Shrimp, though it is usually safe with larger Cleaner or Fire Shrimp. It is also excellent at hunting small bristle worms.
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Tank Mates: Best kept with semi-aggressive companions like larger Damselfish, Tangs, or Hawkfish. Avoid keeping it with shy, passive fish like Firefish or small Gobies, as it will likely bully them relentlessly.
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Social Structure: Only one per tank. They are highly aggressive toward their own kind and other dottybacks unless the tank is massive (500L+).
Ideal Tank Setup
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Tank Size: A minimum of 75L (20 Gallons). While it is small enough for a nano, its aggression is better managed in a larger volume.
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Rockwork: Provide extensive live rock with many small holes and tunnels. This fish needs a complex "apartment complex" of caves to feel secure.
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Reef Safe: 100% Reef Safe with corals. It will not nip at polyps or clams.
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Lid: Like all dottybacks, they are agile and can easily jump through small openings in the tank cover when startled or during a chase.
Why Choose the Diadema Dottyback?
The Diadema is for the hobbyist who wants neon-bright color and a fish with a "big personality." It is an incredibly hardy species that is resistant to most common fish diseases. If you have a tank with robust inhabitants and want a small, active "enforcer" that will keep your rockwork free of unwanted pests like small worms, the Diadema is a fantastic, high-voltage choice.
