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Blue Damselfish

Chrysiptera cyanea

Marine Marine Indo-Pacific Usually captive bred

An astonishingly brilliant electric-blue marine fish, with males often showing vivid yellow tails and fin edges. Virtually bulletproof and suited to beginners, it is nonetheless fiercely pugnacious. In community aquaria, it will harass peaceful newcomers unless added last to a decently sized setup.

Also called: Blue damselfish, Blue demoiselle, Blue devil.

7 cm adult length, drawn to scale. torpedo body.

Saltwater species. The planner judges it with a marine rule set. A reef or fish-only tank takes months to mature and costs more to run than freshwater. See the marine page.

Try it in the planner Opens a tank sized to its minimum with 1 fish added.

What it needs

ItemValueBecause
Adult length 7 cm Used for the Space check: the tank must be long enough for the fish to turn round.
Smallest tank 100 L, at least 80 cm long estimated The least water and floor length this species is kept in for good, as a single fish or smallest group.
Extra water per added fish 25 L estimated What each further fish adds once the minimum is met.
Waste load Class 2 of 5 estimated How much waste an adult makes against its size. Feeds the Load check.
Temperature 23 to 28 C Stock sharing a tank need overlapping ranges.
pH 8.1 to 8.4 Compared with tankmates in the Water check.
Hardness GH undefined, KH 8 to 12 Degrees of general and carbonate hardness.
Flow Medium Low-flow fish are stressed in a strong current.
Light Moderate Matched to the lighting class on the needs sheet.
Group size Single fish is fine Not a schooling species.
Temperament Aggressive Territorial: strong.
Swims in All levels Fish that use different levels share a tank more easily.
Lifespan About 6 years A fish is a long commitment.
Experience Suits a first tank A guide to how forgiving the species is of mistakes.
Salinity Marine, about SG 1.023 to 1.025 Needs salt water, a different build and a longer-running tank than a freshwater set-up.

Tags marked estimated are judged from the size and habits of the species rather than measured, so treat them as a sensible default.

Diet and tank layout

Blue Damselfish is an omnivore that swims in all levels of the tank. It is safe with plants. Give it plenty of cover. It nips fins.

Tankmates

Works with

No close matches in the data. Check the pair tool.

Depends

Nothing flagged.

Avoid

Compare any two fish on the compatibility page, or print the equipment for a stock on the needs sheet. How this is worked out: the method.