Mini brittle star (Ophiothrix spp.) care guide

Group
Other invertebrates
Other names
Mini brittle star (hitchhiker), Spiny brittle star, Hitchhiker brittle star
Family
Ophiotrichidae
Origin
Oceans worldwide, tropical to polar; associated with corals and sponges; arrives on live rock
Water
saltwater
Temperament
peaceful
Reef safe
yes

Care

Ophiothrix is a large genus (about 93 species) of brightly coloured, spiny brittle stars found in oceans worldwide, often living on corals and sponges. Name note: the tiny 'mini brittle stars' that appear as hitchhikers in reef tanks are often not Ophiothrix but other small brittle stars, such as the six-armed, splitting Ophiactis savignyi or the tiny grey Amphipholis squamata, so the name is often applied loosely. Ophiothrix themselves have long, very spiny arms and can grow larger. How they arrive: on live rock, rubble and coral frags. They hide in the rock by day and show only their arm tips, coming out to feed at night or when food is added. Role in the tank: they are harmless, helpful hitchhikers and part of a healthy reef clean-up crew. They eat detritus, leftover food and particles caught on their arms, and some types reproduce in the aquarium. A sudden population boom usually means the tank is being overfed. Caveat: do not confuse them with the green brittle star (Ophiarachna incrassata), a much larger predator that eats fish. They are a common hitchhiker rather than a livestock item. Copper: copper-based medicines and some plant fertilisers are toxic to shrimp, snails and most other invertebrates. Never dose them in a tank holding this animal, and check the label of any treatment or fertiliser before use. Sources: Wikipedia (en.wikipedia.org/wiki/Ophiothrix). Checked October 2026.

Diet

Detritus, leftover food and small particles collected by the arms. Many Ophiothrix hold their arms up to catch suspended food. No special feeding is needed in a mature, fed tank.

Breeding

Some small hitchhiker brittle stars reproduce by splitting (fission), and others brood their young, which is why their numbers can grow in aquaria. Our sources do not describe the reproduction of Ophiothrix.

Compatibility and tank mates

Reef safe and peaceful; harmless to corals, fish and other invertebrates. Eaten by some wrasses, triggers and puffers, and by harlequin shrimp only rarely. Larger brittle star species, not these, can catch small fish.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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