Under Water Dry Zone for Fiddler Crabs




Introduction: Under Water Dry Zone for Fiddler Crabs

I currently have a 55 gallon fish tank up and running, and needed my 10 gallon fish tank that held my fiddler crabs for something else.  Being that fiddler crabs cannot completely live under water and actually need to out of the water, i was left with an issue, the solution, make a dry zone for them.  I have seen a bunch of them for sale, but what is the fun of buying something when you can make it yourself :D

quick list of what you need:

1. clear jar large enough for a couple of fiddler crabs to crawl into
2. Aquarium fish tank air hose
3. Aquarium air pump rated for your tank
4. aquarium air stone
5. sand/gravel
6. (optional) decorations for inside the dry zone

Step 1: Get a Jar

First, get a large clear jar, being that I have a 55 gallon tank, I have enough room for a large "Mt. Olive" pickle jar, luckally for me, my wife likes pickles, I had an empty jar kicking around.  Clean out the jar, if you must use soap, really rinse out the jar, while at it, try to peel off the labels. 

Step 2: Weigh Down the Jar and Fill With Air

Now that you have a nice clean clear jar, need a way to keep it on the ground.  With my set up, I had to put a rock under the back of the jar, filling it half full of sand/aquarium rocks.  Being that fiddler crabs prefer sand over gravel, I filled my jar with sand.  Clear out the area that you are going to lay the jar in.  Keeping the mouth of the jar facing up, slowly submerge it into the water until you the jar reaches bottom.  Slowly tilt the mouth of the jar towards the center of the tank and pile up some sand/gravel at the mouth of the jar to keep it from sliding forward, making sure that the bottom of the jar is at an upward angle.  Next pop the air stone on the end of the air tube that you are going to be putting into the jar, and feed the hose into the jar, if you want to, you can cover the hose with the gravel/sand.   Attach the other end of the hose to your air pump, if you have one, I would suggest an air regulator to adjust how fast the air fills the jar.  The first time I set mine up, I didn't have enough weight and the jar popped off the bottom of the tank.  Just add more sand until your jar stays at the bottom. 
I happened to have a few sponge bob figures and thought it would be funny to have sandy cheeks standing in my dry zone.

Now i have seen a few things that say occasionally turn the air on blah blah blah. I have had my air supply feeding into this non-stop since i first set it up, and the crabs ignore the bubbles escaping the mouth of the jar and chill out there for a while.

As a warning, if you are going to use sand, be prepared to not be able to see inside your tank for a while, sadly because all my sponge bob stuff was in my 10 gallon set up, and I was lazy just scooping the sand and dumping it into my 55 gal set up, I have lost patrick under all the sand, eventually he will show up when the shark decides to move the sand to his liking :D



  • Metalworking Contest

    Metalworking Contest
  • Water Contest

    Water Contest
  • Fix It! Contest

    Fix It! Contest

31 Discussions

aaahh..that explains why the fiddler crabs I had either climbed out or died...they shoulda informed me of that at the pet shop..lol

1 reply

I just found out from the other employees at petco near where iam that the manager says they are fine under water all the time however they and I disagree and see definate signs of distress as now iam on this site looking for way to create a dry zone myself. I think that making money has taken president over what's best for the pets so don't be like me do your homework and now they are of course suggesting a costly solution.It pays to try the diy way

It was the easiest part of making my whole fish tank once i finally understood how to do it. Thanks for this awesome idea!

Thank you for this I made on and it only took a couple of minutes and is a complete life saver

Made my habitat and have a regulator. Have small amount of bubbles from tube and a large one releases every minute or so. Is this sufficient? Guess not sure how much or how little air. Thx

2 replies

it's kinda hard to see, but you want to make sure that crab can get completely out of the water in that air bubble, but it does look very nice.

Yeah I think I need more gravel to make more of a hill into the habitat. He did make it into it and seems to be content but having a hard time maneuvering on the rocks. Will adjust soon. Thx :)

I know this post is a few years old....LOL....but I was just wondering if the crabs will automatically find this dry zone?

1 reply

yeah, I never had to show them the dry zone, I would look at the tank and see them chilling inside of it.

Interesting idea - An underwater beach.
I immediately thought of the treedome when I saw this as well.

1 reply

I did have sandy chilling in there, sadly, I lost patrick when I moved the fiddler crabs into the 55, and added all the sand from their 10

What does he do for food, order crabby pizza? How often do you find yourself having to clean it? Great idea, BTW...

2 replies

they generally eat what is on the bottom of the tank, I have crab pellets that sink to the bottom, but generally it is a mix of the fish flakes, blood worms, and freeze dried shrimp. This has only really been set up for 2 weeks, but I am thinking that it will be an easy, stir up the sand and let the filter suck out the nasty water.

before he died, when i needed to clean it, I would turn off the bubbler, put an air line in the jar above the water line and flood it, then when everything was floating in the water of the jar, turn the bubbler back on but low so it slowly pushed everything out, worked for the 2 months it was set up

I know this may seem like spam to some people but bear with me. I found this ible REALLY interesting, I have been interested in Red Clawed Crabs for a while and bought some this weekend... i have decided to do something very similar if I ever decide to buy a bigger tank... as the commercial underwater lagoons are very expensive. For those who own crab, and would like to help out newbies like myself (or at least follow my progress) please feel free to join my facebook page https://www.facebook.com/redcrabdiaries

It kind of reminds me of this project I want to do, unfortunately not some time soon though.   I thought of getting a plastic tub, attaching many bricks or concrete blocks to the sides of the tub (with ropes and drilled holes) and make an underwater air zone for swimmers in a pool.  A bicycle air pump attached to a hose would connect to the air zone for air circulation.

1 reply

almost the same idea of flipping a canoe over in the water, though I'm not sure that a bike pump would be enough to bring in the oxygen that you would need, if you had a big enough dry zone, and did hydroponic plants, you might be able to get away with one or two people in there for a short time. If built large enough to house a decent sized TV, couple of chairs, and had a pipeline that ran down into the dry zone to provide electrical etc, it would make "why don't you go out and play" much more interesting. I can see it now, "First one into the dry zone gets the good controller"

Do the crabs still try to climb out of the tank, or do they spend most of their time hanging out in their awesome airdome?

1 reply

I have a board that completely covers one side, and the light cover has tin foil around the openings, leaving just enough room for the water to filter into the tank, so far, it keeps them in the tank lol

This is the sort of 'ible that carries the simplicity of ideas that I crave. Regardless of category, if this were in a contest, I would be rushing to cast a vote.