Not furry either, still lovely.
Serpent Star
Ophiarachna incrassata
Also called Green brittle star, Green serpent star, Large brittle star
From Indian Ocean region; records include the Red Sea, the western Indian Ocean, East Africa and Madagascar, the Seychelles and Tanzania.1
At a glance the quick version
Arm-tip to arm-tip span: 10-12 inches (Saltwaterfish.com) up to about 20 inches for large specimens (Reef Builders).
Looks how to spot one
Brittle star (central disc with five long arms)
A big brittle star with a round central disc and five long, bendy arms lined with short spines. The disc is patterned with lighter dots and the arm spines are pale.32
Personality what they are like
A bold, active night-time forager. Unlike most brittle stars it is a capable hunter that can catch small fish and shrimp, so tankmates need careful choice.32
Daily activity how busy a day looks
Roams the rockwork mostly at night, and can lie in wait propped up on its arms.32
Grooming and care the hands-on bits
Keep it well fed and keep water parameters stable; offer meaty foods regularly.3
Home where they are happiest
A marine tank of at least 50 gallons (about 190 litres) for an adult, with plenty of live rock for hiding.32
Food basics what goes in the bowl
An omnivore and predator: eats detritus and standard meaty aquarium foods, and in the wild also hunts small fish and mobile invertebrates.32
Company who they like around
Best with larger, peaceful fish; not suitable with small bottom-dwelling fish, ornamental shrimp or other small mobile invertebrates. Leaves corals alone.3
The story where it all began
Lamarck described the species in 1816. It has long been one of the largest brittle stars seen in the aquarium trade, where it is known for its green colour and its hunting skills.43
Fun facts for the dinner table
- 1
It can ambush a fish by raising its disc on its arms, then dropping down and wrapping its arms around the prey.3
- 2
Large specimens can span around 20 inches from arm tip to arm tip.3
- 3
Like other brittle stars it can regrow lost arms.2
- 4
Its English name in the Catalogue of Life is 'large brittle star'.5
Recognised by the official bits
- Taxonomy (GBIF, Catalogue of Life)
- Described by Lamarck in 1816; accepted name, family Ophiomyxidae, class Ophiuroidea (brittle stars).4
The care rhythm Furry Diary remembers it for you
A typical home-care rhythm for a Serpent Star. It is our own starting plan, not a vet's advice, and you can change every line in the app.
- FeedingDepends on species, many feed from the light and the watervaries
- Salinity checkevery week
- Water testevery week
- Top-upTop up evaporation with fresh RO water, not salt waterevery day
- Water changeAbout 10 to 20% of the waterevery 2 weeks
- Light checkevery month
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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.
- Ophiarachna incrassata distributions (GBIF, from WoRMS) api.gbif.orgused for origin/range
- Green Brittle Starfish (Saltwaterfish.com) saltwaterfish.comused for size, appearance, scavenging, live rock, regeneration
- The Green Brittle Star: Little Fishy, Beware! (Reef Builders, 2015) reefbuilders.comused for size, colours, hunting behaviour, diet, tank size, compatibility
- Ophiarachna incrassata (GBIF species record) api.gbif.orgused for authority, year, classification
- Ophiarachna incrassata vernacular names (GBIF) api.gbif.orgused for common name
Checked 2026-09-30. Text is written in our own words from these sources.