Blue Devil Damselfish

• ExerciseHigh

  A busy, energetic swimmer — keep plenty of open swimming room.

• GroomingRoutine tank care

  Weekly partial water changes keep them in top shape.

• Living spaceNano-tank friendly

  Happy in a small, stable, well-filtered tank.

• Owner experienceSome experience helps

  A little know-how makes life smoother.

• Commitment5–10 years

  Plan for a long, loving relationship.

Health to watch: Ich (white spot) · Fin rot · Parasites

The Blue Devil Damselfish (Chrysiptera cyanea) ranges across the Indo-Pacific and grows to about 6 to 7 cm. Males typically carry an orange or yellow tail depending on the population, while females are uniformly blue with a dark spot at the rear of the dorsal fin. Its colour comes from light-scattering cells in the skin, which is why it appears to glow under blue-spectrum reef lighting. It is genuinely bulletproof at 24-27C, salinity 1.023-1.026, pH 8.1-8.4, and eats flake, pellets, mysis and brine shrimp eagerly. That hardiness makes it a common first marine fish, and the aggression makes that a mistake worth naming: a single adult in a 100 litre tank will claim a third of the rockwork and attack additions many times its size, and removing it later usually means dismantling the aquascape. If you want the colour, plan for a 200 litre or larger tank, add it last, and consider the gentler azure or Talbot's damselfish instead.

• How active is a Blue Devil Damselfish?

  High. A busy, energetic swimmer — keep plenty of open swimming room.

• How much maintenance does a Blue Devil Damselfish need?

  Routine tank care. Weekly partial water changes keep them in top shape.

• What tank size does a Blue Devil Damselfish need?

  Nano-tank friendly. Happy in a small, stable, well-filtered tank.

• Is a Blue Devil Damselfish a good fit for first-time owners?

  Some experience helps. A little know-how makes life smoother.

• How long do Blue Devil Damselfish live?

  5–10 years. Plan for a long, loving relationship.

• What health issues affect the Blue Devil Damselfish?

  Keep an eye out for Ich (white spot), Fin rot, Parasites. These are worth raising with your vet, along with any screening they recommend.

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