Yellowish Filamented Brittle Star — Ophiomastix sp.

Nocturnal scavenger and micro-predator. Reef-safe.

Quick facts

• Adult size: arm span ~15–25 cm; disc ~2–4 cm

• Temperament: Shy, nocturnal

• Reef-safe: Yes (does not harm corals)

• Role: Detritus cleanup, leftover-food scavenger

• Care level: Moderate (sensitive to handling and parameter swings)

Aquarium requirements

• Tank: ≥ 80–100 l with mature rockwork and hiding crevices.

• Substrate: Sand or mixed; not mandatory.

• Water: pH 8.1–8.4, salinity 1.025–1.026, temp 24–26 °C, NO2 0, NH3 0, NO3 <15–20 ppm.

• Flow: Moderate. Needs good oxygenation.

• Cover: Protect pump intakes; brittle arms can get trapped.

Diet

• Feeding: 2–4× per week after lights out.

• Foods: Small meaty items and fine particulates: mysis, chopped krill/shrimp, pellet crumbs. Target feed a piece near its arms.

Behavior and compatibility

• Activity: Hides by day; extends filamented arms into flow to catch food at night.

• Tankmates: Safe with inverts and corals. Avoid predators that nip or eat echinoderms (triggers, puffers, large wrasses, some hawkfish).

• Notes: May steal food from sessile inverts but does not damage healthy corals.

Acclimation and handling

• Acclimate: Slow drip 45–90 min. Match salinity tightly.

• Handling: Do not expose to air if possible; support the disc, never pull by arms.

• Stability: Sensitive to rapid changes and low oxygen. Can autotomize arms under stress; regrows over weeks.

Husbandry tips

• Provide multiple rock caves and shaded zones.

• Spot-feed if the tank is very “clean.”

• Keep iodine and other trace elements within normal reef ranges via regular water changes; avoid copper medications in display tanks.