HCA: Hermit Crab Association

I am concerned about my placement of water dishes. We have two, one fresh one salt, of these fake rock type water dishes:



They sit on top of the sand, giving the crabs an obstacle to climb (albeit only 1" high) to get into their dishes. We don't see our crabs at all during the day, but I know the two smaller ones come out at night (have seen them climbing our cork wall at 2am). Since switching from clam shells (which I were told are too shallow) to these deeper water dishes, I haven't seen much evidence that the crabs are using them.

I see some sink their water dishes in the sand, so the top edge of the dish is at substrate level, which seems like a good idea... until you want to dump and change the water.

Advice?

It can't be that deep into the sand because the sand will suck the water out like a wick and will flood your tank. They are using it, just not dragging crap into it.

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I wonder if hermit crabs can see infrared light. I have a small infrared camera, with small infrared LED's for illumination (not visible). I could make an overnight time-lapse video to record them, if the infrared light doesn't bother them. These cameras are made for night recording applications (eg. monitoring animal activity at night), and give a green and white ("night vision") image.

KellyCrabbieLove wrote:It can't be that deep into the sand because the sand will suck the water out like a wick and will flood your tank. They are using it, just not dragging crap into it.

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Why do you say that? I have my water pools sunk in so the edge is at sand level. The sand never touches the water, other than the bit the crabs drag in.

How do you change the water without making a mess of things?


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I use doubled up dishes. That way I can take the top out and the bottom just sit in the sub and dont make a mess.

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CrabbyEmerson wrote: Why do you say that? I have my water pools sunk in so the edge is at sand level. The sand never touches the water, other than the bit the crabs drag in.

It is a really common problem. So many people come on here distraught because they think there is a hole in their water pools that they can't find only to have it be that. It is just sonething we advise against. If thr sand gets up to the lip enough and the water is full enoufh unfortuneately it happens. Flooding is extremely common with pools sank so deep and flooding kills. I have lost 5...

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Arlo-Duck-Tony wrote:How do you change the water without making a mess of things?


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It depends on the size of the pool. If big people often double up. One stays in the sub and another sits inside of it so you take out the second one and the other stays in place.

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soilentgringa wrote:I use doubled up dishes. That way I can take the top out and the bottom just sit in the sub and dont make a mess.

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I just responded to that post with the same info. Lol

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A lip on the dish doesn't matter. If it's no taller than they are, they will go sideways and hook a leg on it to pull themselves up. They climb trees in the wild, a dish is not an obstacle. However, like the others have said the dishes are too shallow.

wodesorel wrote:A lip on the dish doesn't matter. If it's no taller than they are, they will go sideways and hook a leg on it to pull themselves up. They climb trees in the wild, a dish is not an obstacle. However, like the others have said the dishes are too shallow.

I didn't see anyone else say that. I haven't found any dishes deeper than these, that work in a 10 gal aquarium. They are about as deep as shell height on 2 of our 3 crabs.


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Arlo-Duck-Tony wrote: I didn't see anyone else say that. I haven't found any dishes deeper than these, that work in a 10 gal aquarium. They are about as deep as shell height on 2 of our 3 crabs.


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Sorry, saw all the talk about pools and thought they had. The crabs should be able to submerge, and I thought these only held a 1/2 inch or less. So long as they're deep enough for your guys, great!

They're probably good depth for the two small crabs, but maybe a little shallow for the medium crab. We haven't seen him since we set up the crabitat, tho. Thinking he went down to mold on day 1


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Been reading more, and the more I read, the more conflicting information I find. Almost all commercial dishes made for hermit crabs are 3/4" deep, so likely designed to hold 1/2" depth of water. Most guides say to keep water at this depth or less, and to provide a sponge, while those on this forum seem to contract both points (depth and use of sponge).

I've also seen mention of some using an air stone with an aquarium pump to aerate water and help keep tank humidity up. I like this, as our house is very dry (esp. in winter), and we have to spray frequently and keep tank covered to keep humidity in range. Of course, this may push us toward deeper dishes.

Guidance? What size dishes work well in a 10 gallon aquarium with 3 crabs? What's the thinking behind the various contradicting views on water depth and sponge?