Not furry, but we like them anyway.
Blue Damselfish
Chrysiptera cyanea
Also called Blue devil, Sapphire devil, Blue demoiselle, Electric blue devil, Orangetail blue damselfish
From Indo-West Pacific: eastern Indian Ocean and Western Australia through Indonesia, the Philippines, New Guinea, Taiwan and the Ryukyu Islands to Micronesia, Vanuatu, New Caledonia and Samoa12
At a glance the quick version
Looks how to spot one
Small, deep-bodied damselfish
A small, vivid electric-blue fish. Males often have a yellow to orange snout and tail, while females and young are all blue with a small black spot at the back of the dorsal fin. When it hides in a crevice it can darken almost to black and turn bright blue again within seconds.23
Personality what they are like
A spirited, territorial little fish that likes to guard its own patch of rock. Pairs defend their breeding spot firmly.32
Daily activity how busy a day looks
Busy and active all day, patrolling and defending a small territory.31
Grooming and care the hands-on bits
Easy care. Give it plenty of holes and crevices, especially when it shares the tank with other damselfish.3
Home where they are happiest
A marine or reef aquarium of at least 30 US gallons (about 115 L) with rockwork and hiding places. Saltwater at about 22 to 26 °C, pH 8.1 to 8.4, specific gravity 1.020 to 1.025, dKH 8 to 12. Reef safe. In the wild it lives among rubble and coral in clear, sheltered lagoons and reef flats, down to about 10 m.31
Food basics what goes in the bowl
An omnivore. Wild fish eat algae, tunicates and copepods. In aquariums feed flakes, frozen foods and plant-based preparations.123
Company who they like around
In the wild it lives in groups of one male with several females or juveniles. In aquariums it is often kept singly or with ample hiding places if kept with other damsels.13
The story where it all began
Quoy and Gaimard described the species in 1825 as Glyphisodon cyaneus. It has gone on to become one of the most familiar marine aquarium fish, and LiveAquaria calls it probably the best-selling marine fish in the United States.213
Fun facts for the dinner table
- 1
When frightened it can tuck into a hole and darken to nearly black, then return to bright blue within seconds.3
- 2
Only males usually show the yellow or orange tail, which is why some are sold as 'orangetail' blue damsels.3
- 3
The male guards and fans the eggs after spawning.1
- 4
It has an unusually long list of common names, from 'sapphire devil' to 'cornflower sergeant-major'.2
Recognised by the official bits
- IUCN Red List
- Least Concern (assessed 2021)1
The care rhythm a typical week and year
A typical home-care rhythm for a Blue Damselfish. A starting point, not a vet's advice.
- FeedingSmall amounts once or twice a dayevery day
- Temperature checkevery day
- Salinity checkevery week
- Top-upTop up evaporation with fresh RO water, not salt waterevery day
- Water testevery week
- Water changeAbout 10 to 20% of the waterevery 2 weeks
- Glass cleanevery week
Owner questions the things everyone asks
How often should I feed my Blue Damselfish?
Feed your Blue Damselfish small amounts once or twice a day. Furry Diary's starting plan suggests daily feeding. This keeps your active fish happy and healthy.31 Pet Wiki plan
What does a Blue Damselfish eat, and what should it never eat?
Your Blue Damselfish is an omnivore and enjoys flakes, frozen foods, and plant-based preparations. What it should never eat varies by individual; ask your vet or a good breeder for specific foods to avoid.321
How much space does a Blue Damselfish need?
A marine or reef aquarium of at least 30 US gallons (about 115 liters) is recommended. Provide plenty of rockwork and hiding places to match its active, territorial nature.31
What temperature, light or water does a Blue Damselfish need?
Keep the water at 22 to 26°C, pH 8.1 to 8.4, specific gravity 1.020 to 1.025, and dKH 8 to 12. Lighting needs vary; ask your vet or a good breeder for specific advice.31
How often should I clean a Blue Damselfish's home?
Furry Diary's starting plan suggests cleaning the glass weekly, testing water weekly, and changing 10 to 20% of the water every two weeks. Top up evaporation daily with fresh RO water. Pet Wiki plan
Can a Blue Damselfish live with others?
Yes, but it is territorial. In the wild it lives in groups, but in aquariums it is often kept singly or with ample hiding places if kept with other damselfish. Provide plenty of crevices to reduce aggression.31
How long does a Blue Damselfish live?
Lifespan varies depending on care and environment. For a reliable estimate, ask your vet or a good breeder who knows your fish's background.
Can I handle a Blue Damselfish?
Handling is not recommended as it can stress the fish and damage its delicate slime coat. If you need to move it, ask your vet for safe methods.
Written from the sources on this page, a few checked guides (VCA, ASPCA, RSPCA) and Pet Wiki's own starting care plan. A friendly guide, not a vet's advice.
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Yellowtail DamselfishWhere this comes from
Every fact on this page has a numbered source. Spotted an error? [email protected].
- FishBase: Chrysiptera cyanea, Sapphire devil fishbase.seused for distribution, size, depth, habitat, diet, social structure, breeding, IUCN status
- Wikipedia: Chrysiptera cyanea en.wikipedia.orgused for common names, colours, taxonomy history, breeding
- LiveAquaria: Blue Damselfish liveaquaria.comused for aquarium care, tank size, water parameters, colour change, popularity
Checked 2026-09-30. Text is written in our own words from these sources.