Ask Milo

The hermit crab advice column, Ask Milo.

Ask Milo – Is beach sand safe for hermit crabs?

Laureen asks:

I purchased a little crab at the wildwood boardwalk a few days ago. Yikes, I bought everything wrong ( now that I am doing my research after the fact). So… I rushed out and bought a 10 gal tank to get the little guy out of that cutsie boardwalk cage and off those dyed stones. Ive also ordered a recommended substrate, but it will take time for the handling and shipping process to get here. I live a short distance from the Atlantic Ocean (8 Miles) and am wondering if it would be ok to go to the ocean and grab some wet sand next to the surf and use that in the meantime until the substrate gets here. …And if this is acceptable, would you recommend mixing the substrate with the beach sand?

Hi Laureen,

If it’s the only sand you can get right now then yes get some sand, take it home, wash and bake it. Many crabbers use playsand or a mix of playsand and coconut fibre if they can’t get beach sand. Do a google for ‘hermit crab safe playsand’ for some ideas of brands.

I’ve used sanitised beach sand myself without any problems.

Please make sure it’s legal to collect beach sand before doing so. In some areas it is prohibited.

Your friend in a pinch,

Ask Milo – Brown beetles in the crabitat

Alison asks:

I have small brown beetles in my crab cage. They are not on the crabs and they are not mites. They move very fast and hide under the bowls and there are dozens and dozens of them that come out at night to eat crab food. I suspect they may have hatched from some of my high-end crab food. Any ideas for getting rid of them short of dumping the entire sand/sphagnum substrate (very large cage with six inches of substrate…weighs about 75 pounds so hard to deal with.)

Hi Alison!

It’s difficult to know what kind of bugs you are dealing with without seeing a photo. We have a couple articles that might help:
Household mites and bugs

Guide to bugs you might find in your crabitat

Ask Milo – What size tank do I need?

Mattiesse ask:

I am the proud owner of 4 beautiful crabs in Brisbane. the problem is, is that I live in NSW so my other parents in queens land need to take care of them. luckily im bringing them down here but I cant bring the tank, so im gonna have to make a new home. im planning on getting more hermit crabs as well so I need to know how to make the best sized and equipt tank for soon to have not 4 but 6-8 hermit crabs. how big should the tank be and what is the best stuff to get for them so they live a long healthy life!!!

How exciting! The amount of space you need depends on the size of crabs and the number of crabs. Long term you should have 10 gallons of space per crab so you would need at least an 80 gallon tank if you are going to keep 8 hermit crabs. That will give them plenty of space in your crabitat as they grow. You will need a lid that can hold in the humidity, a proper heat source, a day time light and about 12 inches deep substrate (mix of play sand with a bit of cocofiber mixed in). Also food dishes, saltwater and fresh water ponds (deep enough to submerge in), gauges, places to hide and things to climb. Oh and yes a bunch of shells!

For more details check out some of our articles:
Hermit Crab Essentials Shopping List
Newbies Guide to Hermit Crabs

Ask Milo – Hermit crab is surface molting

Kendahl asks:

my hermit crab just started molting a few days ago and we put him in an ISO tank but he is completely out of his shell and surface molting. I know thats not good for a hermie but for some reason he just wont dig. i’ve been checking on him and hes still alive and doing fine, hasn’t ate his exoskeleton yet. I’m worried he’s not going to molt properly and die. is there anything I can do to get him to dig underground? or should I just leave him alone?

Dear Kendahl,

It depends what your ISO looks like. If it is pretty bare they can get stressed. If the substrate isn’t easy to dig in that could also be the problem. Can you describe the ISO set-up?

What I have done in the past is dig a small hole in slightly damp sand/ substrate and put the crab and shell in the hole and cover with a flat clam or scallop shell or something you have to create an area for the crab to calm down. A hidey hut made from a coconut shell also works well if you have one.

I’ve had crabs successfully surface molt but this technique has worked for me in the past. One of my crabs then dug down after he had the energy to do so. It is also important that your ISO has correct humidity levels, especially if the crab is out of its shell – that’s where they keep their water reserves.

I have gently helped crabs into their shells only two times successfully out of three attempts (different crabs). Usually if you dip the shell in fresh de-clorinated water and lift the crab gently and curl the abdomen into the shell and put your hand near its eyes it will back into the shell. I have only tried this with strong, healthy crabs – I would be very very gentle or not do it at all if it was going to stress out a crab that had, say, lost limbs due to stress. If you don’t think you should risk helping him into a shell then the other suggestion I have is to offer larger shell that has water inside already, for him to back into.
That has worked for me in the past. They can’t really carry the shell but they have the protection and water reserve.

I hope this helps and please reply with a description of your ISO set-up.

If you don’t have hearing and humidity required you might need to put him back in the main tank with a soda bottle ISO unit over him. Instructions can be found on CSJ – search for ISO.

Your friend in a pinch,

Ask Milo – Vertical tanks

Finn asks:

I don’t have a lot of horizontal space in my house–is it okay to have a small-based but extremely tall tank for hermit crabs, basically with the necessary deep sand, but with multiple ‘tiers’ for them to climb and bathe and hang around?

Yes so long as your substrate is sufficiently deep and with a smaller footprint you may want to make the substrate even deeper than recommended so you don’t have a problem with molters crowding each other. The base should allow for both water dishes as well. Making multiple tiers is a great idea. You can also use fish netting and other climbables to make every vertical surface climbable. Stop by the forums for suggestions from our members.

Your friend in a pinch,

Ask Milo – New crab is burrowing

Hermie Newbie asks:

I just got new hermit crab. Now I have two. I have only been a hermit crab owner for a few months. Long story short, I got two from a friend. Anyway one of them died so I got a new one yesterday. He keeps borrowing. Is that normal? Should I do anything about it?

Hi Hermie Newbie,

Yes, burrowing after purchase is very normal. Normally they don’t have the right substrate or substrate depth to do so and really enjoy it when they can. He could be ready to moult or just wanting to recover from Post Purchase Stress.

Please join the Chewin the Choya forum on CSJ and reply to the topic introducing yourself 🙂

Your friend in a pinch

Ask Milo – Black Tahiti Sand

Jan asks:

I have a 55 gallon aquarium that was used about 6 months ago for tropical fish. It has Black Tahiti sand and I am wondering if I can move my 3 hermits from their 20 gallon over to this type of sand? Has anyone else used this substrate for their Hermes? Is it safe or too coarse?

Hi Jan!
I’ve looked up this type of sand as I am not familiar with it. The version I saw was a fine grade. While aquarium sands are ‘safe’ they really aren’t an ideal substrate unless they meet the need of being able to pack and hold like a sand castle. Sand that is too fine will often clump and stick to your hermit crabs. This could be dangerous if it dries and hardens. Sand that is too coarse will not pack properly. The ideal substrate allows for successful molting. The best substrate is play sand mixed with a small amount of cocofiber. There are various suggestions as to ratio but you should have more sand than cocofiber. The cocofiber allows for moisture retention and some aeration. You can add additional items to the substrate too (things like orchid bark, oyster shells crushed, leaf litter). If you still want to use your black sand you might be able to put it to use in your water pools.

Your good friend in a pinch,

Ask Milo – I need some DIY hermit crab toys ideas

Anna asks:

I have been having some trouble finding a good way to make some fun toys that my hermit crabs would love. My Crabitait is plain With nothing for the hermit crabs to really do. I have some branches that they don’t like and a lego 2nd floor which they dont go on unless i put them on there(though they LOVE to hangout under it). Plus the toys at the pet store are to expinzie for my buget. I want them to love there cage. Do have any ideas for homemade toys that would make my hermit crabs have a better time in my cage and make it feel more homie?

Our members are very creative at making DIY toys and fun things for their crabitats. The best way to get ideas is to ask your question on our forums! Here is a tutorial on how to make your own mangrove tree. Here is another article on cost cutting tips for setting up your crabitat.

Happy DIY!

Your friend in a pinch,


Ask Milo – Removing mold or mildew from wood

Anna asks:

How do i get white fluff mold from my old cage off of my half log hut with out burning it?
Dear Anna,
The white fluff mold is not at all safe for your hermit crabs!. If the half log hut is small enough, I recommend placing it a pot of boiling water. Boiling it for 15 minutes or so should be good. Then place it on a cookie sheet and turn your oven on a low setting like WARM or 200F. This will provide a low heat for thoroughly drying the half log hut. This temperature is safe and will not burn the wood. If you don’t feel safe doing that I would suggest placing it outside in the bright, hot sun for a couple days.
Hope that helps!
Your friend in a pinch,

Ask Milo – Can two different size hermit crabs live together?

Froggy Kisses writes:
Dear Milo , My crab Crab Cakes has sadly passed away recently and my other crab Sebastion seems depressed . My sister also has a crab but he is about 10 times larger than Sebastion . Will her crab Bam Bam hurt Sebastion ? And besides him interacting with Bam Bam is there anything I can do to help ?
Dear Froggy Kisses,
I am so sorry to hear about your Crab Cakes dying. 🙁 While some people may disagree there is no reason a large crab would harm a small crab. Think about how hermit crab gather in huge groups in the wild… we don’t separate ourselves into colonies based on size! We all hang out together and Sebastion and Bam Bam can definitely be friends.  Hermit crabs are not true hermits and absolutely enjoy the company of other hermit crabs so long as there is enough space in the tank for everyone.
Your friend in a pinch,