Halloween Moon Crab Care

*This post has been updated since it was originally written- I have learned a lot since then and sadly Winston is no longer around after a failed molt.

Hey there :) I decided to make a post today featuring my good buddy, Winston! Winston is a halloween moon crab or Gecarcinus quadratus. He is an adorable little crab. I had a really hard time finding good care information for him so I will summarize what I have in case anyone else wants to care for one of these awesome creatures!

Housing: So, when I did my reading, I saw in several places claims that one of these crabs could live in a ten gallon and a couple in a twenty gallon. I’m going to call BS on that. In order to meet all the requirements for this species, a twenty gallon is the minimum for just ONE. The more space the better. I have Winston in a twenty now and I wish he had more space!
*Updated info: I would not keep one in less than a 40 gallon breeder at this point and still feel that more room would be better! Some feel that you should have more than one for their comfort and their habits in the wild, however be aware that they can be territorial as well. If you keep multiple, add more space and make sure you only have one male.

Substrate: For my substrate, I mixed coconut fiber, jungle soil mix, calcium sand, and sphagnum moss. The reason for mixing all of these is that the crabs need a substrate that can hold moisture, but also one that can hold shape well and is easy to burrow in. These crabs love making little tunnel systems! This mix has worked out really well for me. Due to the burrowing habits, these guys need at least several inches to work with. Also, anytime I have a tank that will be kept moist, I create a drainage layer. There are multiple ways to do this. Usually, I just use an inch or two of gravel, but recently I discovered little clay balls designed for drainage called hydrotons I believe. This is much less heavy so I will probably go with this method from now on. Once you put down a few inches of the drainage layer, lay some sort of mesh over it to separate it from the substrate. It is good to have water that comes halfway up this layer but does not touch the barrier. This drainage layer will really help the tank stay humid without being over saturated or moldy, trust me!
*Updated info: These days I would keep them like I keep my hermit crabs. That would be with a mix of sand, coconut fiber, and organic soil with some additions like leaf litter, moss, rocks, crushed cuttle bone etc. I would not recommend calcium sand. You can provide calcium through offering a good diet. I would create a thick layer of substrate to hold humidity and tunnels, maybe 8-12 inches at least. In nature they burrow 3+ feet down. I think this was a big reason my poor guy couldn't molt well. You want the substrate to stay moist enough to hold burrows but not wet.

Water: These crabs need access to both fresh water and salt water. Fresh water is more important for them to wet their gills. I use a larger dish for this (just make sure they can easily get in and out so they do not drown!) In a different place in the tank, I keep a little pool of saltwater. I believe this provides for their mineral needs somewhat. Keep in mind they do not swim so dishes need to be easy to get in and out of and not too deep. *You could put a bubbler in the fresh water to help with tank humidity!

Decor: Make sure to provide hiding places for these guys; they are pretty shy. You can use cork bark, other types of wood, hidey huts, fake plants, plants safe for amphibian enclosures, etc. If you have more than one crab, you’ll definitely need multiple hiding places so they have somewhere to go to avoid aggression. They also love to climb and are sometimes found in trees so include some branches like cork bark, cholla, etc.

Temperature and Humidity: Keep the temperature between 78-90 degrees F. I would recommend a gradient so they can self-regulate. Humidity should be high, around 70%

Food and supplements: I always keep a piece of cuttlebone in the tank as a source of calcium. Winston likes to scrape away at this sometimes. These crabs are omnivores. They looove fresh fruit. They can also eat greens, scrambled eggs, fish, crickets (dead or alive I believe), and hermit crab food or pellets. As long as you provide a varied diet, they should be healthy. I try to feed him fruit, greens, and eggs whenever I can. He loves the fruit in particular. I have tried blueberries, black berries, banana, mango, cantelope, strawberries, etc. Other things I have heard they can eat include seeds, peanut butter, mealworms (freeze dried), sardines, chicken, and apple sauce!

Other information: These guys molt once in awhile and from what I understand it can be very hard on them. When they are molting, they may bury themselves in a humid location, they may go limp. You should not bother them at all during this time or it could kill them. They are very vulnerable in this state. If you have more than one, this is the time they may likely try to kill one another.

Also, sometimes these crabs make little clicking noises. I am not sure if this is a distress signal or not. You can gently handle these crabs. They are pretty calm as long as you are respectful of them. I gently coax Winston onto my hand to pick him up; I do not grab him. Once they are on your hands, just keep them flat and let the crab walk over them as you place your hands in front as he walks. The only time I was ever pinched was my fault for grabbing him. If you play nice, so will they. Remember how scary it could be for them to be handled by a giant! If the crab does pinch, be sure not to pull away or you could injure the crab.

Has anyone else had experience with these guys? If so let me know!