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 Furry Diary remembers it for you
A typical home-care rhythm for a Blue Damselfish. It is our own starting plan, not a vet's advice, and you can change every line in the app.
- 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
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Where this comes from
Every breed page shows where each fact comes from. If we got something wrong, sorry, we are pet people, not a science magazine. Tell us at support@furrydiary.app and we will fix it.
- 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.