Brittle Star
Ophiarachna sp.
A fast, reef-safe scavenging star that hides by day and cleans up leftover food (avoid the green species).
| Difficulty | Beginner |
| Min. Tank Size | 110 L |
| Temperature | 24.0–27.0 °C |
| pH Range | 8.1–8.4 |
| Max Size | 15.0 cm |
| Lifespan | 3-5 years |
| Diet | Scavenger |
| Temperament | Peaceful |
Overview
The Brittle Star (Ophiarachna sp.) is a fast, reef-safe scavenging star that hides by day and cleans up leftover food (avoid the green species).
This guide explains what the Brittle Star does for your reef, how to care for it, whether it is reef-safe, and what to watch out for.
What It Does for Your Tank
It is a clean-up crew member that eats detritus, leftover food and waste, helping keep the sand bed and rockwork clean.
Care Level
It is hardy and easy, ideal for beginners, as long as it is acclimated slowly and the tank is mature.
Water Parameters & Acclimation
Keep a stable reef system at 24-27 °C, pH 8.1-8.4 and salinity 1.024-1.026 (35 ppt). Hold alkalinity at 8-12 dKH, calcium at 400-450 ppm and magnesium at 1300-1400 ppm, with ammonia and nitrite at zero. Stability matters more than chasing perfect numbers, so test regularly and avoid sudden swings.
Like all marine invertebrates it is very sensitive to copper and to sudden changes, so never use copper-based medications in the tank and always drip-acclimate new arrivals slowly over an hour or more.
Feeding
It feeds on detritus and leftovers. In a spotless tank, drop in a little sinking food now and then so it has enough to eat.
Is It Reef-Safe? Compatibility
It is reef-safe and peaceful with corals and fish - a trusted clean-up crew member. Provide one hiding spot per animal and avoid overstocking your clean-up crew, or some will starve.
Common Problems & Care Tips
The biggest risks are copper exposure, ammonia spikes and rushed acclimation - go slow and keep water stable. Snails that fall over should be turned upright; provide spare shells for hermit crabs to prevent squabbles; and never buy a clean-up crew bigger than your tank can feed.
Is the Brittle Star Right for Your Reef?
The Brittle Star is an easy, useful addition for almost any marine tank. Build a balanced clean-up crew rather than relying on any single species, and pair it with our marine fish and coral guides.
