HCA: Hermit Crab Association

I have 6 crabs now. My mom died and I took in her two in May.

They are as follows (based on how long I’ve had them)

Brownie - tennis ball sized, 8 years

Stripes- tennis ball sized, claw and legs bigger than Brownie’s, but not in a bigger shell yet, 8 years

Teeny - a little bigger than a gold ball, 4 years

Micro- little bitty, was in a shell the size of a nickel when we took him in last year. Now in a golf ball size shell but he can retract way in.

All my existing crabs have molted successfully more than once.

Two New guys- golf ball sized shells, on it seems proper size, the other is much smaller with skinny little legs. They molted at my mom’s in a much smaller but similar set up (my old tat).

Possible 7th, but I haven’t seen her in over a year. Dora I would have had 9 years, she went down to molt in fall 2019 and never came up. Teeny is wearing her shell. I’m assuming she didn’t survive that molt, but Stripes did a 10 month molt, and she was pretty big so you never know. At that time I only had 4 crabs including her.

I have a 40 breeder that’s really stable and self sustaining. I have 10-12 inches of substrate lower on the water pool side. It’s EE and play sand, originally about 1:5 but who knows now. There’s also moss to dig in. The base is 36x18. I only pick up dropped food, clean the water dishes and occasionally wipe the inside walls with a damp paper towel. I haven’t churned the sub since I got new carpet a few years ago. The tar is way too heavy to move.

I have a two level moss pit with an additional 2-4 inches of reptile moss on the ground inside and behind an upside down basket and a low rim basket of moss on top. Second level is only about 6x10.

Salt water IO and fresh water in ceramic crocks deeper than the largest crab with river rock in the bottom and needlepoint plastic ramps. There are two half hollow logs placed vertically and a hollow cork log vertically, two tall chollas, several shorter chollas, two coconut huts and lots of silk and plastic foliage. All that plus a gajillion extra shells from small to jumbo $$$ takes up about 60% of the surface level and the rest is open except the two small food dishes.

My temps and relative humidity stay stable. Wet side stays 80/85 on both. Dry side (which is also the pool side, go figure) stays 80 is on heat and 70/80 humidity with UTH across that short side and most of the back on that end.

After what now appears the have been a mating episode between Stripes and Teeny, I have been considering that I probably have too many crabs for the space. I brought the last two home to get them somewhere they’d be cared for, but wasn’t really planning on adding more to my little colony, especially as two are already XL going on jumbo.

So if you made it through all of that, I’m looking for suggestions. I’d rather build up than add a second tank. Next beat option would be increase tank size fast while all 6 are up. They are tunnelers AND climbers, so you never know, and idk when the new two last molted.

When calculating space for crabs, it's the floor space molting space) that is important for determining how many crabs of what size in what size of tank. So altho building up is your preference, it won't increase the floor/ molting space, so I would increase the tank size instead.

curlysister wrote:When calculating space for crabs, it's the floor space molting space) that is important for determining how many crabs of what size in what size of tank. So altho building up is your preference, it won't increase the floor/ molting space, so I would increase the tank size instead.

If I build up, I can further deepen the substrate and offer more running room, giving climbing and activity space up higher. They’re very much “tree crabs”.

I’d have to go up to a 75 gallon to get more base, and it won’t fit on the table.


Here’s 5 or the 6 clustered in a log right now.


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It is good that they are active climbers, but as Curly said, it's the molting space that is most critical. You are right that you could increase the volume of the substrate if you add toppers, but the "footprint" of the substrate is also very important. Tunneling crabs will often dig all the way down to the bottom (no matter how deep the sub is) and then tunnel along the bottom quite some ways. I suspect that in the wild they may dig several feet down to construct a molting cave; deeper would certainly be safer from all kinds of possible predators (including their fellow crabs); that's impossible in our glass-bottomed boxes.

So, it multiplies the risk of molting cannibalism any time you add more, no matter how big the tank is; but giving them a larger footprint helps to mediate that somewhat. And as you have seen, adding crabs to an established pair or group also causes other upheavals among the group as well. So ideally, maybe it would have been better to keep the two groups separate. But the bottom line is that you can only do what you can do, and it is really great that you are working so hard to give all these crabs the best captive home they can have. If you can give them a larger tank overall, that is always going to be better, but if you just can't really do that right now, for whatever reasons, but you can build up, then that also will be better than what you have now.

I really applaud your conscientious efforts to take the best care possible of these crabs. Having recently lost my father, I know that it can be a lot to deal with, in all kinds of ways you never even think of before it happens, and it really counts for a lot that you are working so hard at this very difficult time for you, to care for these little creatures, too. Bless you and your family.

Thank you.


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