The Post – Extra! News on Preparing the Fiddler Crab Nursery

So you’re like me and you’ve got a pregnant female fiddler crab. Now what?

Well, we just came home from Petsmart with a second 10-gallon tank, lid, light, and pump/filter assembly so I can set up a saltwater aquarium in which to put the babies. Maybe I’m crazy for trying to see if I can raise them …?then sell them? but the challenge of motherhood calls. My husband, a geek of a different nature, respects this need in me to see if I can do this. He quietly acknowledged that he would “understand and be willing to fund” a second tank for the “kids.”

The dilemma now is did I wait too long to get it set up and get the “nitrogen cycle” started before she releases the babies? I can take a patch of the filter gauze from my current tank, which is loaded with nitrogen-fixing bacteria, and put it in the new filter to “seed it” with bacteria.

Tomorrow I’m going to Fish Pros in Raleigh NC to get another good-sized chunk of live rock. Between the filter seeding and the live rock, that should get the water parameters in the safe zone and the bacteria up and running quickly. Also the live rock will provide calcium for the many molts the little ones will need to go through.

What I was not sure though was how I would be able to “catch” the babies since I won’t know when she releases them and I won’t know if they’ll be too small to see once she does. Also, should I make the second tank a regular “salt-water” tank to represent the “open ocean” like most fiddler babies go to, or make it brackish like what they’ll end up in? This last question got further complicated by the information I found on the blog below that indicates I should isolate mom before she releases the young. So I have much to ponder tonight while I get this up and running.

I did a search for info on pregnant fiddler crabs and come up with The “Dear Blue Lobster” blog entry” from July 25, 2007. The Dear Blue Lobster site claims to have been answering “your crustacean questions since 2002.” This entry is from someone who is concerned that her fiddlers make have “hooked up” and now what should she do? She is freaking out at the prospect of a 100,000 babies in her tank.

The gentleman who runs the blog gave good technical advice on taking care of the pregnant mom, saving the larval babies, raising them, and even indicated how much/lb. you can sell fiddler crabs for over the internet. The crustacean guru also gave the following emotional advice:

“So what do you do if your female is indeed pregnant? Comfort her. Her man has kicked her out and will no offer care for her children — in fact, he may try to eat them! ….Good luck to you and your Fiddlers. Motherhood is a special blessing indeed.”

Since it is well past July 2007….I wonder how the mom (human) and the mom (fiddler crab) made out with their situation? For myself, we shall see. I am off to set up the tank. I guess I’ll set it up brackish and isolate mom before she “delivers.” I have also emailed Dear Blue Lobster for help on what I should do. I’ll keep you posted on his reply.

I recommend the blog. The crustacean guru is Christopher Chimwish. His site description is as follows:

Christopher Chimwich received his MMN in 2000, specializing in decapod behavior. He is currently surveying benthic decapod populations in the Indian Ocean for his doctoral thesis. Chris answers questions about crustaceans, covering everything from DNA mutation in African crayfish to Fiddler crab sign language.

By the way, if you want to be a real geek, apparently the term for my fiddler crab when they have the brownish eggs attached to their abdomen is being “in berry.” So.

If you want to know what he has to say about fiddler crab sign language, click here.

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6 Responses to “The Post – Extra! News on Preparing the Fiddler Crab Nursery”

  1. Laurie Says:

    Laurie’s Fiddler Crab fry–March 17th, 2008, Day 7 and still going…

    Just an update. They were released on March 10th and true to the (artist!?) breeder of the mangrove crabs http://www.aquahoito.info/sesarma/index.html on March 15th, day 5, I had a little more than half die off. In the last 2 days no more have died, tho.
    Today I was able to get supplies for them, including a salinity meter ($7.00) and some test strips for nitrate/nitrite etc. and Kent’s PhytoPlex (not live) for more food. As I didn’t have proper food for them I did the newborn fish fry trick of feeding them hard boiled egg yolk. About 1/2 a matchstick head’s worth smashed fine in some water and dispersed with the fry, twice a day. That was too much, no doubt, but I’m new at crabs and they did ok…

    I tested my water (2 gallon hex w/no filtration, slight bubbling from airstone) and nitrates were 0, nitrites were alright-“caution” .5 ppm, salt is .015ppm, hardness 300 (ideal). I’m finding it’s cheaper to do water changes in a small fry tank than buy a whole salt water filtration system. 2 tbsp Ocean Reef salt/quart, 1 qt every couple days. The little squirts only have to get to 2 or 3 months old before they’re little crabs, by the looks of Mr. Mangrove Crab’s work, so that’s not much salt used over time versus the complexities of a nitrogen cycle filtration system. Now that I have test strips I’ll know how often that should be.

    Again, shutting off the bubbler, wiping the bottom to free the slime that’s growing there (I don’t think I’m getting it all, so if it’s food it’s still present somewhat), then fluffing it to one side and siphoning it up w/airline tubing seems to clean the nitrite creating stuff pretty well. Shining a light in one corner for them to aggregate near keeps most of them out of the way, and I shine it again in the gunk glass I siphoned into to get the ones I accidently sucked up back into the tank.

    One interesting note is that after the “D-Day” day 5 die off the herd that is left swims less and congregates on the bottom on the side facing the window. Their movement is now more like a thousand little frogs hopping around in the herd at the bottom of the tank. Some still swim, but majority is doing the new movement. I can see a bit of their tail now, but no major growth change.
    Possible theories: 1.) they molted on day 5 and many didn’t make it through. 2.)Nitrites killed them at this stage and they haven’t molted yet. 3.) Maybe everyone’s dies at day 5 because they have 5 days of food stored in them or because when they molt the new contact with water conditions isn’t right for them…
    Interesting to note that my water isn’t the right ppm for salt, but half have survived… I thought I saw somewhere it should be ocean water (1.020-1.024, and somewhere else 1.010. hmm. Wish I had more tanks to test all 3 salinities.

    My hope is that with more postings from folks that are having success we can all help eachother out to solve this mystery and not make silly statements like it taking hundreds of thousands of dollars to get the right water conditions for this. heh heh that one still makes me chuckle. I bet it’s possible.

    Folks could try their filtration systems in their nursery tanks with a big ball of fiber-fill around the intake (intake on LOW!) with super fine cloth over that. That makes the drag into the intake almost nothing. You’ll see if the babies are being pulled onto it, it’s too strong still… but I still am having great water results with one gallon of water in a two gallon tank.
    Best… Laurie

  2. Kelly Says:

    My female crab released her eggs about 3 weeks ago. there have been tiny little bug like things swimming in the tank since then. I have a 6x magnifier and when looking through it these things do not look like any of the pictures of crab larvae posted on the web., How do I know if these moving specs are my baby crabs or small bugs in my tank? They crawl on the rocks and float/swim around they are whitish gray and round. They do not seam to have a tail as pictured on the web. Please help this is the only blog (re: scarlet o hara) that may give me some insight.
    Thanks

  3. Hyena-chan Says:

    Hello there could you give me a bit of info on breeding them, i do have 2 of each and if they do breed id like to try to raise them tho i hear its really hard ovbiously, im having a bit of trouble understanding some of the stuff you said above, so if you could email with a bit of info more indepth that would be much appreaiated
    radioactivehyena@hotmail.com

  4. Melody Says:

    Hey there! I’m so glad I found this web page. I brought home a female fiddler crab for my male Eugene and by day 2 I noticed she was already carrying eggs. I don’t know if they already mated or if she was already “fertilized” by the time I brought her home, but I know for a fact yesterday her “egg flap” was empty.

    Anyway, I’ve been looking up information about raising the babies and have had close to no luck at all. Most resources I’ve found so far have said it’s “impossible” to raise them in captivity (though I never believed that), and it’s great to hear from someone who’s actually attempted it.

    I’d love it if you could share some tips or suggestions for a low-budget nursery (I’m a little financially strapped at the moment). I read online that the incubation period is 14 days, so I figure that I have about 2 weeks to get everything set up.

    It would be fantastic to hear about your success in raising these little guys!

  5. 2010 in review « Soul Mosaic Says:

    […] The busiest day of the year was August 6th with 66 views. The most popular post that day was The Post – Extra! News on Preparing the Fiddler Crab Nursery. […]

  6. cheri fertsch Says:

    Kelly
    im in the same situation my crab had babies in aug of 2010 and it is april 2011 and they are the same way. And she is pregnant again. I separated the male from the female to see if there is any differance hopefully. I read they need to be in the ocean to mature to full but i cant find the website where some one has fully completed the breeding from babies to adult and i cant find it.

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