Halloween Hermit Crab
Ciliopagurus strigatus
A striking orange-banded algae-eating hermit; mostly reef-safe but provide shells.
| Difficulty | Beginner |
| Min. Tank Size | 75 L |
| Temperature | 24.0–27.0 °C |
| pH Range | 8.1–8.4 |
| Max Size | 5.0 cm |
| Lifespan | 3-5 years |
| Diet | Algae grazer |
| Temperament | Peaceful |
Overview
The Halloween Hermit Crab (Ciliopagurus strigatus) is a striking orange-banded algae-eating hermit; mostly reef-safe but provide shells.
This guide explains what the Halloween Hermit Crab 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 part of the clean-up crew, grazing nuisance algae (film, hair and slime) off rock and glass and helping keep your reef tidy.
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 mostly feeds itself on the algae in your tank. In a very clean tank, supplement with dried algae (nori) or algae wafers so it does not starve.
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 Halloween Hermit Crab Right for Your Reef?
The Halloween Hermit Crab 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.
