Green brittle star (Ophiarachna incrassata) care guide
- Group
- Other invertebrates
- Other names
- Green serpent star, Green brittle sea star
- Family
- Ophiodermatidae
- Origin
- Indo-West Pacific from East Africa to New Guinea and the Philippines; reef flats, seagrass and rubble at 1–20 m
- Water
- saltwater
- Temperature
- 24–27°C
- pH
- 8.1–8.4
- Hardness
- SG 1.023–1.025, dKH 8–12
- Minimum tank
- 200 litres
- Care level
- intermediate
- Temperament
- aggressive
- Reef safe
- with_caution
Care
The green brittle star is a large, bright green brittle star with a disc of up to about 5.5 cm and long, banded, flexible arms, so a mature animal spans many times the disc width. It lives on shallow reef flats in the Indo-West Pacific, under coral rubble, among seagrass and algae. Behaviour: unlike most brittle stars, which are harmless scavengers, the green brittle star is an active predator. It hides under rocks by day with its arms out, and catches and eats small fish, shrimp and other small invertebrates, especially at night, by curling its arms around prey and pulling it to its mouth. This is why it is marked with caution for reefs and given an aggressive temperament. Set-up: a large tank (200 litres or more) with plenty of rockwork and caves; keep it with fish too large to catch. Keep salinity stable and acclimatise slowly by drip, as echinoderms do not tolerate sudden changes. Reef role: it does not eat corals and will scavenge leftover food, but it is not a safe clean-up animal for tanks with small fish or shrimp. Copper: copper-based medicines and some plant fertilisers are toxic to shrimp, snails and most invertebrates. Never dose copper in a tank holding this animal, and check fertiliser and medicine labels before use. Sources: SeaLifeBase (sealifebase.se/summary/Ophiarachna-incrassata.html). Checked October 2026.
Diet
Predator and scavenger of small invertebrates and fish. Feed pieces of fish, shrimp, mussel or mysis to the arms two or three times a week; a well-fed animal is less likely to hunt tankmates.
Breeding
Brittle stars mostly have separate sexes and release eggs and sperm into the water; some species brood their young. It is not bred in home aquariums.
Compatibility and tank mates
Keep with fish larger than about 7–8 cm and with corals. Risky with gobies, blennies, firefish, cardinals, small wrasses, shrimp and small crabs, which it may catch. Harmless to corals. Large triggers and puffers may attack it.
Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.