# Fiddler Crabs



## Guest (May 12, 2006)

Just wondering if any one has put a fiddler crab in with Cobalts. I have a fairly large floor area (22"x36"), but that dang claw looks pretty deadly.


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## defaced (May 23, 2005)

I wouldn't, though I've never worked with them so I don't know how apt they are to snapping.


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## jbeetle (Feb 8, 2004)

I think the males have that large claw mainly for display. I am not sure how dangerous they'd be, but that claw is very imposing.


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## zaroba (Apr 8, 2006)

i think they also use it to fight with other males over females.

even though most petshops keep fiddler crabs in fresh water, they need brackish water. keeping them in freshwater greatly reduces thier lifespan. don't know how well a frog or tadpole would take to slightly salty water.


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## Guest (May 12, 2006)

Well, I put him in there, and am watching very closely. The crab is VERY timid as would be expected in new surroundings. I'm hoping that he(she) will eventually migrate and hang out in the stream area up front. The frogs like to chill in the moist areas from the drip wall in the back.


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## themann42 (Apr 12, 2005)

like said above, the large claw is basically used for attacting females and fighting off other males. other than that's it's pretty useless from what i read. they use the little claw for sifting through sand for food.

crabs are scavengers, so theoretically he should be ok. however it really depends how hungry he gets. if u keep him well fed i'd like to say it should be ok, but you never know for sure. offer him a variety of foods to see what he likes to make sure you keep him full.

i keep crabs with fish fry, and i've never seen him go after one. through counting fish i also know i've never lost one. however i have seen a crab go after one of my larger fish. my guess is the larger fish get the food faster, so the crab goes hungry sometimes unless i put some veggies that sink to him.

hopefully all goes well for you. let us know how it goes.


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## Guest (May 13, 2006)

If mixing different species of frog gives the inhabitants stress then I would imagine a crab would do the same. Even though the big claw is useless don't they have another smaller one? Sounds like trouble


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## chuckpowell (May 12, 2004)

Fiddler crabs dig deep, long burrows, they also need brackish water. A Dendrobatid set up is really sub-par for a fiddler crab. You'll likely end up killing it and possibly the frogs also. Not to mention the crabs likely to tear up the tank a bit.

Best,

Chuck


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## slaytonp (Nov 14, 2004)

While I have had no personal experience with fiddler crabs, I did put some red clawed crabs in the paludarium once, in the aquarium section. They didn't stick to the aquarium, but invaded the land portion as well, devastated some foliage, took over the frog caves and were generally a pain in the butt. While they didn't actually injure any frogs, they sure disrupted everything. If you introduce fiddler crabs, make sure they remain strictly aquatic.


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## c'est ma (Sep 11, 2004)

Well, I haven't had fiddlers in pdf vivs, but have had them in a _Bombina_ tank for more than 2 years now. It was more by coincidence than design, but toads, crabs, and zebra fish have coexisted well...It began when I ended up with 2 fbts, a trio of fiddlers (1 male, 2 female), and needed to consolidate. I added some wood & philodendron to the crab tank, added the fbts, and held my breath. 

It turned out to be one of the most interesting assemblages I've ever had. For the most part the toads & crabs ignore each other. However...to heck with the notion that fcs are scavengers! Turns out they love live crickets. And what they have in common with fbts is the quality of being mindlessly intent on food items--or what they think are food items. And, unfortunately, an fbt cannot distinguish between a lively dusted cricket and a waving fc claw. I'd add crickets, all would converge on them, the fbts would try to eat the male crab's claw, he'd bop them on the nose or even pinch them, and they'd disengage, only to repeat the scenario the next time they crossed paths. Amazingly enough, neither species seemed the worse for wear from these encounters. Not sure I'd want a crab pinching my pdfs, though...

As the female fcs don't have the big white claws, they don't elicit the feeding reflex of the fbts, so they coexist even better than the male with the toads. (Interestingly enough, the male crab, which was always waving its claw around, would not entice the fbts unless they were already in a feeding frenzy from the fresh addition of live crickets.)

And as for the fcs requiring brackish water--I worried about that, but the 2 female crabs are still going strong after more than two years, so I'm not sure that's strictly true. (Unfortunately, the male didn't make it through one of his molts...tho he also thrived for a couple of years.) The crabs even bred in the tank.

Here are some pics:

Not a great shot, but it shows the male fc and one of the fbts on the same cork raft. This fbt always comes to the front and begs when I approach. This pic shows that the crab and the toad ignored each other unless both were going after crickets. (Emergent _Cryptocorne_ leaves behind them.)









This is a shot of one of the females when she was "pregnant." The roe/larvae grew between her body and one of her plastral plates.









Another poor shot (wish I'd noticed how dirty the glass was!), but this was of the female when she was releasing her larvae. The cloud of black dots in the bottom corner is crab larvae. The fish were gorging on the larvae. Of course, none of the larvae survived in the fbt tank. I transferred some to my nano reef, but of course that was no go, either. (Here's where you need the brackish conditions, no doubt.) I did get some pretty cool movies of the larvae through my microcscope while they were still alive...










And, just for the heck of it, some shots of parts of the tank with the fbts visible. In one of them you can see some of the snails that also thrive in the tank. This surprised me--I would have thought the crabs would eat them. 

My little beggar again (snails on the leaves under the raft): 









Both fbts, sword plant, crypt, & philo:









BTW, for many years I had great success keeping terrestrial hermit crabs in "woodland" vivs with green and brown anoles. The crabs even eat lizard feces. They do like to burrow under plants, though, and so create a little havoc. Also, they will eat lizard eggs if they find them. 

--Diane


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## c'est ma (Sep 11, 2004)

Just adding a fts I found, with fbts at surface and male fiddler on substrate:










--Diane


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## Guest (May 19, 2006)

Update on "the Riddler" ...after 6 days, he seems much more comfortable as he has established his own stompin grounds. He likes the waterfall run-off area to bask, while staying close to the stream where he can jump in and forage on the fish s**t...

(Added)
The 3 cobalts that were the first tank inhabitants, kept clear of this watery area from the start , are not shy and always hopping around and foraging on the forest floor part. The gecko's are active in the upper foliage with good colour which is a good indication of security and comfort.


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## c'est ma (Sep 11, 2004)

That sounds like a very interesting assemblage. I just looked at your paludarium page--WOW! It is gorgeous. The contrasting plastic laminates look great.

Have you thought of adding a female crab? Have you noticed your male going after live insects?

--Diane


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## Guest (May 19, 2006)

> Have you thought of adding a female crab? Have you noticed your male going after live insects?


When I bought the crab, I was not aware that it was a brackish creature. I didn't want to get a second until I'm sure that they will survive in freshwater. 
I see by your earlier post that you had good luck with your crab in freshwater. If he does well I will get him a GF.
Haven't noticed him eating any ff's yet.


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## Guest (May 23, 2006)

Hiya i just read this post for the 1st tme, and i realise that you've already put him in there, but i'd still advise you take it out. I owned fiddler crabs, and some other species at various times in my tropical fish tank and all of them used to try and snip at the fishes tails. All it takes is for it to get a bit more confident and your frog will be maimed or history. 
Once he got accustomed to the tank,my crab actually used to hide under a rock and wait till fish swam past then poke his claw out and snippy snip snip! luckily the fish could swim away so he never actuially killed any, but i doubt a frog would be as nimble, and also frogs can get easily stressed, and i dont think it'll do the frog any good to be avoiding a potentially harmful crab all the time.

Its just a matter of time my friend..... please keep a CLOSE eye on it if you must keep it in there.


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## Guest (Jun 9, 2006)

OMG you put a crab in there!!!!
Im afraid to touch crabs let alone put one in with an amphibian.
Is it safe? I suppose it is if you are posting it.


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## Guest (Jun 10, 2006)

Update on the fiddler crab.
I found the little guy dead. Although he didn't cause any problems in the month that it was in the viv, I wouldn't get another one. Pet stores should be a little more precise on selling a brackish fish/animal as freshwater.


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## c'est ma (Sep 11, 2004)

Aw, sorry to hear that, and I agree with you about the responsibility of pet stores.

I think my unexepected (and undeserved, given that I, too, knew little about them at purchase) success with the fiddlers may have a lot to do with the fact that I use my very hard well water in the Bombina tank. In a dart tank with RO water filtering through coco, etc., things are probably way to acidic.


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