Caribbean Hermit Crab — Fact Sheet

Coenobita clypeatus · Caribbean Hermit Crab

📋 At a glance

🏠 Enclosure

• For a small group start with a securely covered 90 × 45 × 45 cm tank; larger crabs and groups need more floor area.
• Prepare spare natural shells before arrival.
• New animals need separate observation with suitable humidity, pools and molting substrate, not a dry quarantine box.

🪨 Enclosure furniture

• Use at least 15 cm of sand-rich substrate, or three times the height of the largest crab, whichever is greater.
• A roughly 5:1 mix of washed play sand and coir should hold a tunnel without dripping.
• Do not routinely turn or replace occupied molting substrate.

💡 Lighting

• Provide a 12-hour light cycle with shaded hiding places and darkness at night.
• UVB is not an established minimum requirement.
• Do not use coloured night lamps or direct sun through glass; warming must not destroy the humid environment.

🌡️ Temperature

• Maintain air around 25–28°C, with nights approximately 24–26°C.
• Measure above the substrate where the crabs move.
• If needed, mount thermostatically controlled heat on the outside back above substrate level, never beneath the molting bed.
• Monitor more than one point and keep pools away from electrical fittings.

💧 Humidity & water

• Maintain about 75–85% humidity.
• Provide separate dechlorinated freshwater and marine-saltwater pools, each deep enough to submerge the shell, with secure ramps usable by the smallest crab.
• Prepare salt water with marine aquarium salt according to its seawater directions, not table salt.
• Change unfiltered pool water frequently and remove waste immediately.
• Sponges do not replace pools.

🪳 Diet

Staple foods — follow the feeding schedule:

• Offer varied small meals daily: unseasoned animal protein, vegetables, some fruit, leaves and suitable seeds.
• Remove perishable leftovers before they spoil.
• A single pellet, sweet fruit or coconut alone is not a complete diet.
• Avoid salt-seasoned human food and pesticide-treated plant material; never use aquarium medications without confirming crustacean safety.

In moderation:

• Sweet fruit is a small part of a varied diet, never the only food.

Avoid:

• Pesticide-contaminated food, spoiled leftovers and unverified wild-collected foods.

Supplements:

• Keep a clean calcium source such as cuttlebone available.

🩺 Health — warning signs

• Burial can last weeks or longer during molting; do not dig an animal up.
• Sudden shell abandonment, repeated aggression, foul flooded substrate or surface molting demands careful assessment of humidity, shells, diet and disturbance.
• Protect a vulnerable surface molter from tankmates without touching its soft body.
• Seek an exotics veterinarian experienced with crustaceans for injury or ongoing decline.
• A shed skin alone does not mean the crab has died.