HCA: Hermit Crab Association

We got two class hermit crabs about 2 weeks ago. They've seemed well adjusted and happy in their new environment. Since we came back to school yesterday (Monday) morning after the weekend, one of the crabs seems to be missing. We assume it's buried under the substrate and molting, but can't find where. Should we be concerned?

First off what size is your tank? How deep is sub? Heat and humidity? Number of shells available? Diet? Water?
These will help me understand the situation better.

Thanks!
We have a 10 gallon tank. The substrate is moist but we don’t have a hydrometer in there so I can’t say exact humidity levels. It’s about 3” deep. The crabs are both small still. We have 6 extra shells in there which all seem to have slightly bigger openings than the crabs are in now. They have fresh and salt water and their food is pellets.

Here's basic care:
1. Substrate needs to be more than 6 inches. 3 times the height of your largest crab.
2. Heat needs to be 75-82, although they can handle and seem to enjoy higher heat. I use UTH (Under tank heater) duck-taped to the back of the tank. Heat is very important.
3. Humidity- 80 percent is recommended. 3-5 shells for each crab is recommended.
4. Never dig crabs up. It's probably buried and de-stressing or trying to molt.
5. Dechlorinated and saltwater. There are water dechlorinators for reptiles you can but, and Instant Ocean sea salt.
6. Diet should be a mix of protein, calcium, fruits, veggies, plant litter, and other yummies that are safe for them, never that bad store-bought food. It ain't good for them.

I doubt your crab escaped. They are master hiders! If you still have questions about their care I'd be happy to answer. I would recommend visiting the care guide (here):viewtopic.php?f=28&t=92457
Also, crabs shouldn't be handled daily, if that's what you're trying to do- Not saying you are just putting it out there. They are prey animals and get stressed very easily.

What type of lid does the tank have? Is there any holes they could wiggle out of? Crabs can and have climbed silicone seals, so if the top isn't properly secured, yes they can and will eventually make a break for it and leave the tank.


If the crabs are very small, 3 inches of substrate is perfectly acceptable providing that its at least 3x as deep as your crab. Anything more is a bonus! 6 inches is purely recommended as it at this depth it provides enough height for most crabs smaller than a medium.

Thanks! I doubt it escaped. It’s a mesh lid with no holes and a peg that keeps it shut. We have been handling them every day, because the person at the pet store told me TO do that! How often do you recommend handling them? And we’ll definitely work on getting them some better food. Thanks for all your help!

Nice. If you don't live in a tropical climate keeping the screen covered will help keep in heat/humidity! ^_^

Many crabbers are hands off, however if you do handle I recommend waiting until they moulted in captivity prior to handling to ensure they are well adjusted. Keep handling time brief, as it can stress them out until they become acclimatise to handling (only handle crabs thats on the surface and not hiding away).

Thanks!! That’s definitely important info!!

This really isn't something you need to go buy, as crabs can eat nearly anything pesticide+ additive free, but my crabs love the food from HermitGrub. You can find her shop on Etsy!

again not necessary but I still do recommend her shop!

Good to know! I’ll check out the shop when we need a refill