Adding New Crabs to Crabitat

[smcgarvey]

Hi, I recently lost 1 of my hermit crabs which I'm fairly certain the remaining crab may have eaten while it was molting. We have a 20 gallon tank and I recently added several new hermit crabs. Should I take the ones that are really little out and in their own tank vs. leaving them in with my "big guy?" Most of the new ones are hiding and have been since I got them about 3 weeks ago, sometimes see them at night. I am just paranoid that he will start going after them, although he has never shown any aggression in the past 2 years. Thanks.

[odelayheehoo]

Hello, welcome to the forum!

Typically, you can mix various sizes of crabs together without an issue, but if one is known to be interested in being aggressive, then it might not be a good idea. If you don't mind, there are a few questions we would like to ask to get a better understanding of what your tank is like, since there aren't any pictures.

How deep is your substrate? If it's deep enough, it shouldn't be too easy for a crab to find another molting, but sometimes it does happen.

Do you have any extra shells in the tank, if so, how many? You'll want to ensure they are the proper size for each crab in the tank, and that they are preferred shells with the correct opening shape. You can view the shell guide here:
https://www.hermitcrabassociation.com/p ... 24&t=92552

What kind of foods do you feed? It's very important to offer a variety of different foods, especially calcium and protein respectively. If they lack these nutrients, it's common for a crab to go after another as a source of protein.

It's common for crabs to dig underneath the substrate or hide frequently after you introduce them, as they tend to "de-stress" during this time, especially when purchased from a pet store.

[smcgarvey]

Thank you so much! My tank's substrate is about 5.5 inches deep. I have a mix of coconut soil bedding and sand, both moist. Temperature in the tank ranges from 77 - 80 degrees, humidity is normally around 70%. I have all kinds of food, some store bought, but most recently through someone on Etsy who prepares various types of hermit crab foods. I do use a calcium supplement that looks like a white powder, once a week mixed in with the food. I took the smallest crab I could find out and in a 10 gallon tank that I have as a spare. As far as shells, yes I do keep a variety of shells in the tank. My big guy has 2 shells to choose from, I actually got a video of him getting into one of them, but seems he was trying it out as minutes later he was back in his!

[odelayheehoo]

It would be ideal if you could keep it at or above six inches deep, or three times deeper than your largest crab is. Increasing the substrate depth will allow for crabs digging underground to molt properly, and decrease the risk of them being found by the others.

What kind of calcium powder is it? You can use it, but it can’t have any added D3, pure calcium carbonate is best. I offer powder made from crushed up cuttlebone in a dish, you can also use the whole cuttlebone.

It sounds to me like your bigger crab may have found the other molter, or he could have been overly stressed from PPS (post purchase stress) which is also a huge factor with new crabs.

[smcgarvey]

Thanks again for the response. The calcium supplement I use is, Thrive Calcium Supplement, says it helps produce healthy growth and exoskeleton formation. The crab that I lost was one that I had purchased together with the big guy. It would have been 2 years this August since I got them, that's why I was shocked the one didn't return, I only found an empty shell and nothing in the substrate. They have molted together several times and sometimes separately. How often should the food be changed when they're molting? I'm wondering if I didn't leave enough food out and maybe they were coming up from the substrate at night. I was changing it out every 2 - 3 days when they were under versus daily. As far as the newbies being scared, how long can they go without food/water? I've seen 2 of the 5 I bought but not the other 3 but they are really small too.

[odelayheehoo]

It looks fine to me, didn't see D3 added mentioned on that product.

Oh, so this crab isn't new then...understood! I would support the possibility of him being attacked during a molt, that seems most likely given your details so far. I would definitely recommend increasing the depth of the substrate.

If both are underground at the same time, you should monitor the activity for a little while. You can add food during this time because sometimes they do dig back up during the night. When they molt, they consume the necessary amounts of food and water to last them the entire time. They won't starve, because they can eat the substrate if they need to.

[smcgarvey]

Thanks! As far as my new hiding hermit crabs, would you be concerned that is has been almost 3 weeks since seeing them? 2 have been out, mostly at night but no sigh of the other 3.

[odelayheehoo]

No, they can stay underground during a molt for more than a month, depending on the size, longer than that is not unusual.

[GotButterflies]

Hello! I just wanted to mention a few things and add some links.

I recommend that you get your humidity up. IMO it needs to be a minimum of 80. Hermit crabs have modified gills, and need humidity to breathe. IMO heat lamps are terrible at making the humidity evaporate, so I personally do not like them. A vast majority of crabbers use the ultratherms to heat the air instead of heat lamps. I personally prefer glass tops, however with glass tops you cannot set heat lamps on top of them. Heat lamps can crack glass lids. With mesh lids you can cover them in Press-N-Seal, or cut open gallon sized Ziploc bags and tape them to the outside with packaging tape to help keep the humidity in the tank.
Humidity boosters: Bubblers definitely do help boost the humidity. Double dish bubblers: http://hermitcrabassociation.com/phpBB/ ... r#p1030806
You can also add moss pits to help. You would use organic moss (as well as moss that is on the safe list), and moisten it with dechlorinated fresh water. Then, put the moss in a shower caddy or a glass vase laying on it's side so the hermits can walk in and out of it. Glass tops also help keep humidity in.

Calcium should be offered at all times.

Hermit crabs can eat a lot of the same things that we eat. Just check to make sure the item is on the safe list. Foods should be organic when possible. Hermit crabs are sensitive to pesticides and fertilizers.
You also want to provide one or more calcium sources at all times. Examples would be Cuttlebone, Organic Eggshell, Oyster Shell, Lobster Exo, Shrimp Exo.
Make sure you cover all aspects of food pyramid
Safe food list: http://hermitcrabassociation.com/phpBB/ ... 25&t=92557
Unsafe food list: http://hermitcrabassociation.com/phpBB/ ... 25&t=92556
Food pyramid: http://hermitcrabassociation.com/phpBB/ ... 25&t=92554

The HCA recommends 3-5 shells per hermit crab. I personally recommend more. It never hurts to have more There are incorrect shells to buy. Here is the shell guide: http://hermitcrabassociation.com/phpBB/ ... 24&t=92552

[smcgarvey]

Thank you so much for this additional information. Ironically, this morning my humidity is at 81%. I use a mister to spray each morning, particularly the climbing sticks, plants and empty shells. Out of curiosity, how large is your tank? I find mine which is a 20 gallon feels cramped with the few things I have in it. My big guy constantly likes to bury underneath the water dishes, so every morning the water dishes are just about empty due to the amount of substrate that has gotten inside of them. I have a few climbing rocks for them and some fake greenery to climb. Since this is an actual fish tank, my top is a hooded top with a day and evening light, but I really don't use the lighting feature. In my previous and 1st crabitat, it was just that - made for crabs. But my big guy learned how to climb the glass walls and would walk along the mesh top, eventually making a big hole in the top!

[GotButterflies]

Yw! Misting can lead to flooding, so it really is best if you can avoid doing that.

More than likely your crab is burying under the water dish because it is nice and moist under there.

My tanks are fairly large. I have a 100g with a 67g exo terra topper, and two 75g with 50 gallon exo terra toppers.

Hooded tops are going to be really hard to keep the heat and humidity in. Perhaps you can look on craigslist, offerup, letgo, varage sale, 5miles, facebook marketplace for a different lid

[smcgarvey]

Thank you again. So what kind of top do your tanks have out of curiosity? I do have 2 heaters (on the side) of my tank too.

[GotButterflies]

I recommend glass tops. They help keep humidity and heat in.