Hello, and some questions...

[bloopdaloop]

Hiya!

I'm new here and to hermit crabs in general, and I'm slooowwly setting up my tank (so that I can research everything and set it up properly). I have an old fish tank which I plan on using to start with, and if need be upgrade it when needed; though I'd prefer to keep them purely in this tank if that is at all possible (though I'm strongly guessing it's not, and I certainly don't want to treat my crabs cruelly!). As such I have some questions:

My tank size is: (L) 55 (W) 29 (H) 45 cm (roughly 72 L)
or roughly (L) 21.6 (W) 11.4 (H) 17.8 inch (roughly 19 gallons)

1. How many full grown crabs (if any) could I keep in this size tank? If I cannot keep any full grown crabs in a tank this size, then I'd like to get 4 smaller crabs and transfer them when they are at an appropriate size. So with that in mind:
1A. How big should they be when I transfer them?
1B. What dimensions would their new tank need to be once they were fully grown?
1C. How often do they molt? (So I can determine how long I'd have before I needed to get them a new tank.)

3. Would this setup work/make my crabs happy?:
For my current tank, I'm thinking about putting a container in my tank which is large enough for some small/medium sized crabs to fully immerse themselves in the saltwater, whenever they wish (though only deep enough to cover the top of their shells). For entrances/exits, I'd either make a ramp or use aquarium silicone to glue to something to the walls of the container so that they can climb out. And if I can find something that fits (I already bought the container, before realising that I should double-check to make sure this scenario is okay), put in a fake plant and/or hang a fake vine off the ceiling (which will hang next to a hammock).

4. Where do I put the heat mat, and roughly what size would I need for my tank? I've heard arguments for both underneath or on the back of the tank, and I'm a bit confused as to what's right. Also:
4A. Would putting an aquarium background and/or wall type of decoration affect the heating of the tank, if I have to put the heat mat on the back of the tank? - I've got some leftover bamboo privacy screen which I used to decorate my patio, and I was thinking of using both to decorate my tank. I'd use the aquarium backing to decorate my tank so I don't have to look at my boring wall, and the bamboo on the inside of the tank so that the crabs can climb on it.

5. Would this setup work?:
I'm thinking of building a wall out of popsicle sticks and hot melt glue (which I've been told it is safe for the crabs), and using that to separate the deep-digging substrate area from the rest of my tank. On the other side of the tank I'd have the saltwater container (if possible) or just have reptile carpet as the substrate, with decorations that they can climb on. I'd slide the wall closer to the centre of the tank as they grow larger, so that they have plenty of space to burrow without interference from the other crabs.
I would like this setup so that the crabs don't accidently dig around (potentially) unstable decorations and crush themselves, while also saving money on the digging substrate, as I can just wash the reptile carpet.

[GotButterflies]

Hello Welcome to the HCA! I recommend that you read our care guides that are located in the forum.

Your tank will work! As far as how many it will hold, it will depend on how large the hermits are, and if you plan to upgrade their tank in the future. I personally think the method with hermits is just like a marine saltwater fish tank. Get one as large as you can - you will always want larger! It is an addicting habit.

Heat mats belong on the back of the tank, above the substrate line.

Substrate should be at least 6" deeper or three times the depth of your largest crab. It should be playsand and eco earth - mixed to a 5:1 ratio. It should be moistened with dechlorinated freshwater or dechlorinated marine salt water. It should also be the ENTIRE length of the tank. Molting space is extremely important.

I don't recommend the bamboo wall - it will mold. As far as using hot glue - that is safe, but the humidity (if held at the right humidity) will cause it to fall apart).

Pools should be deep enough for them to fully submerge in and safely get out of. A lot of us just use tupperware containers.

Good luck!

[aussieJJDude]

Hello! Welcome!

As for the questions - just my opinions.

1. Depends on the species of crab. Looking at your profile, mentioned you come from Australia - eyyyh (same!)!! Most likely you're going to keep C. Variabilis, which I find tend to be pretty active and enjoy space - even if they dont get as large compared to other species. I do like that its a tallish tank, aussies do appreciate a nice deep substrate IMO.

If this is going to be their permanent home, I would suggest a pair. Otherwise, I would suggest upping to a 4fter (4ft x 1.5ft x 1.5ft min, which is a pretty common size and holds around 246L) for a group of 4, of any size.

I personally reccomend 1 crab for every 900 cm^2 of surface area, doing so I haven't run into many problems and each crab still has enough space for moulting - which tends to be a major issue for many hermit crab owners IMO.

As for transferring, it can be anywhere from 'now' to a couple of years down the track, depends on the size of the crab and the rate in which they are growing IMO. Smaller crabs moult more frequently - usually around once a moult - but smaller durations, while larger crabs moult every 6 - 12 months, but takes 'longer' to do so.

2. The setup sounds good. I still encourage to have a deep enough bowl for freshwater, they still use freshwater quite regularly!

3. As for heatmat, you want something large enough to fit on the entire back of the tank, above the substrate line. Sidenote, I've found pet store UTH (heatmat) to be a complete waste of money, and some of the UTH from Ebay not only preform better - from my experiences - but cheaper.... so would suggest checking out ebay if you haven't already!

While traditionally a UTH is used underneath the tank for the conventional reptile setup, it doesn't do much good for a crabitat, since you want to heat the air (not the substrate) and the thick layer for substrate does a great job in trapping all the heat in the substrate.

As for aquarium background, they can be used depending on the brand of UTH. Some don't do well.
I find that the plastic plant mats (squares) commonly use in aquariums (found in petstores/ebay) or cheapish tacky groundcover in the garden (bunnings has this) works well in having a background and still allowing ample heat through... plus crabs can climb it - and also found they enioy hiding in it as well... a few suction cups to hold them up, and bobs your uncle!

4. As for the whole half and half, while I do agree above with GB, in an appropriately sized aquarium the half/half thing can work out well... I would suggest a larger tank personally, since your tank footprint isn't very big and will quickly fill up. Plus more substrate is never a bad thing.


(In saying that, I did the half/half thing without issue on my older crabitat... the crabs did fine, just was a reduction in moulting space, which ment a lower number of crabs)

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[bloopdaloop]

Thank you both for replying so quickly! Your wonderful answers have given me a few more questions:

1. aussieJJDude (Aussie! Aussie! Aussie! Oi! Oi! Oi! ) surprised me by saying I could keep 2 full grown crabs (presumably the C. Variabilis - which makes sense considering Australia's strict animal importation laws), so my question is; is 2 crabs enough company, since they're social creatures? If they'll be happy with just 2 then that's what I'll do, but as I said I don't want to treat them cruelly, so if more is better I'd rather just end up getting a larger tank.

2. I went to the pet shop the other day to buy some supplies, and the lady there said that hermits are ectothermic, so the heat mat needed to be only at one end of the tank (though she was referring to it being underneath the tank) so that they can self-regulate their temperature. However, aussieJJDude said that the UTH should cover the whole back wall... so, I guess I'm just checking to see if that changes things or not. I'm a worrier when it comes to my pets, I just love them so much that I don't want them to suffer! ♥

3. How deep should their freshwater dish be? The dishes the pet stores provide have always seemed a bit to shallow for my liking, but I was considering using them since they didn't need to immerse themselves in the water - however if they aren't deep enough, what would be the minimum depth?

[Motörcrab]

Hello and welcome.

to answer your questions,
1. Once again the number of crabs is dependant on the size and their personality. Some will do fine having less room and others rather have their space. We have some crabs that seem to stay by themselves and others like to be with a group. It's really hard to tell with them unfortunately.

2. aussieJJDude is correct. You want the UTH to go from the top of the substrate to the upper rim of the tank and cover that entire area. Where I live I also place a UTH on one side of my tank to get my temperature higher. If you read through the Crabitat section you will see most of the topics are of people with low temperatures. 95% of them are due to not having enough surface area for heating. Also the back of the tank will naturally be warmer next to the heat source so if a crab gets too hot it can just sit at the front of the tank to cool off or even take a swim if need be.

3. The water pool depth depends on the size of the crabs. I use 5 cup (1.18L) pools on my tank with my strawberries. They are about 4 inches (10.16 cm) deep but my guys are between a tennis and golf ball size. Most of us use plastic food containers. Generally most stores have tons of shapes and sizes to choose from and can find the perfect size. They are way cheaper than buying actual water dishes. We will also use two containers for each pool. one will always stay in the tank as a shape holder for the hole then you remove the top one with the water in it. It helps when crabs decide to dig under them and molt. The second container reduces the chances of disturbing them or collapsing their tunnel. I like to zip tie crafting mesh (plastic sheets with tons of little holes) to the sides of the pools for them to climb in and out.

On a side note, I always wanted to go to Australia. It's just so far and expensive from the US. There was talk of the company I work for doing work there but am unsure if that is moving forward or not.

[aussieJJDude]

1. Haha! Oi. Oi. Oi all the way!
Crabs are social to a degree, but I've never really noticed my aussies being social in comparison to my straws - and whhat others describe. Even then, they do fine in pairs. As long as they have a (species) buddy, they do fine.

But from my experience, aussies need space. I find them to be a little aggressive at times, not to mention their activity level.... they need space IMO. I tend to understock by this forum's standard, and rely on floor space as a measurement for the amount in a tank.... since using surface area, I have not run into issues.

2. Has answered that rather well above... so no point in rewording what I think.

3. Deep as you want it. I reccomend deep enough that they can submerge themselves if needed, around 3 - 5 cm min would do well.

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[bloopdaloop]

Thanks for your help!

On a side note, I always wanted to go to Australia. It's just so far and expensive from the US. There was talk of the company I work for doing work there but am unsure if that is moving forward or not.

I know what you mean, I'd like to visit the US one day but the travel prices are ridiculous! - Well if you ever do end up out here, I'm sure you'll enjoy yourself!