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FAQs on Brackish Water Crabs, other Crustaceans

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Fiddler crabs versus peacock eel 10/21/08
Hi
<Hello,>
I have a freshwater tank with three gold fiddler crabs, one male and two female.
<Uca spp. are brackish water animals... don't last long in freshwater conditions... On the plus side, at least some Spiny Eels tolerate brackish water well, and may even be healthier in it than freshwater.>
Well I got a peacock spiny eel, who was about 5 inches, and the next morning he was being eaten by the female crabs.
<The eel died; the crabs ate the corpse. Spiny Eels die very easily, frequently from bacterial infections. For example, they can't be kept in tanks with gravel. Must be sand. Gravel scratches the skin, allows bacteria to get past the mucous layer, and within days they die. This happens SO OFTEN that it is depressing. Brackish water around SG 1.003 (as opposed to "teaspoon tonic salt per gallon" nonsense) may be beneficial to Spiny Eels because it minimises the risk of bacterial infections.>
I don't understand what happened. He was perfectly fine all day long... and I know that my tank is in great condition.
<Do you have sand or gravel in the tank? If gravel, that's likely part of the issue. Spiny Eels are also easily starved. You can't keep them with things like loaches and catfish because they don't compete for food. If you stick one in a community with loaches and catfish, it will get steadily weaker with time. They obviously don't eat flake or pellets, and need a meaty diet of things like earthworms or frozen (not freeze dried) bloodworms. Just getting food into them is hard enough without keeping them with other nocturnal fish that steal the food first.>
Is it possible that the crabs could have killed the eel?
<No. Uca spp. are primarily detritivores, though they will eat carrion.>
The eel was somewhat slow moving and was still very young. I am very upset about the eel, it was very beautiful and I would really enjoy having an eel in my community tank.
<Sadly, these aren't "easy fish" and I'd encourage you to read my thoughts here before doing anything else:
http://www.wetwebmedia.com/FWSubWebIndex/spinyeelsmonk.htm
>
Ashley
<Cheers, Neale.>

Please Read ASAP... Fiddler crabs... missing legs... poor English... too typical no reading, understanding of animals needs 8/5/08
Yes,
<Yes?>
I would like to know if you could help with my fiddler crab... I just bought it 2 days ago and I have just notice... that its missing 3 legs...yeah....where he has his huge claw. which I know its a male.
<Likely shock from poor handling, maintenance. Will grow back if looked after properly. Fiddler crabs (Uca spp.) are of course BRACKISH to MARINE water organisms that shouldn't be kept in freshwater tanks. They need more land than water. Like to burrow. Keep in an vivarium (not an aquarium) with maybe an inch or two of warm (~25C) brackish (SG 1.005-1.015) water with a big sand bank (coral sand and silica sand mixed 50:50). Stabilise the sand with bogwood roots and various stones, ideally calcareous ones like tufa. Fiddler crabs are NOT compatible with fish. Period. They are too easily damaged by them, and aquarists that are keeping fish invariably have the wrong tank for Fiddler crabs. Fiddlers are omnivores and need a mixed diet containing small invertebrates and algae. Bloodworms, Sushi Nori, catfish pellets, algae wafers, etc. would all work well. Gregarious; keep in groups of six or more, with more females than males. Males will display to one another but rarely cause physical damage if given adequate space. Great escape artists!>
Can you please help me I don't know what to do? should I return it.
<Hope this helps, Neale.>

Mangrove "swamp"/ mudskipper, fiddler tank? 7/31/08
Hi Crew (or should I say crew member),
This is 40 gal des (not sure anyone remembers her). I have a bee in my bonnet (or perhaps gobies) as I have a new project idea. My tank has been fallow for ages now, and I was paging through the book by "The Complete Aquarium" by Peter Scott. Anyway, I came upon the Mangrove swamp with the mudskippers and fiddlers and I was utterly charmed.
<It is indeed a lovely aquarium.>
Anyway, I have been researching this topic-- where to get the critters and plants, how to raise mangroves, what to put in the tank, how much water and sand, brackish, the range of topics. But a few things seem blurry to me (well more than a few...), but I 'll try for brevity.
<Would highly recommend looking over Richard Mleczko's chapter on mudskippers in my 'Brackish-Water Fishes' book. He's easily the world expert on keeping these fish in captivity, and discusses every aspect of their care as well as all the different species you'll see on sale. In fairness, the chapter on Mudskippers in the Aqualog Brackish Water Fishes is also very good.>
So here it is--
Basic setup: 40 gal breeder and stand; Orbits' compact florescent (2 92 watt bulbs).
Plans: Replace actinic bulb with 6700K and keep the 10,000K.
<Do make sure the tank is "mudskipper-proof", as these fish will climb out of any gaps they find.>
Divide tank roughly in two with plastic, rock up to about 8 inches or so. Place (no.? ) potted mangrove trees grown from seeds (already with leaves, etc) around mostly one side.
<Mangroves grow very slowly, and you may find plastic plants or houseplants in plastic pots (to keep the salty water out) will work at least as well. Plants like Philodendron work very well for this sort of thing.>
Fill around with (? type sand-- oolitic, aragonite, etc?) about one inch on one side and about 1/4 to 1/3 on the other
<Sand type doesn't matter, but a mix of coral sand and smooth silver/silica sand is probably the best in terms of appearance and "stickiness". The coral sand will also add a bit of buffering to the system.>
fill with brackish mixed water 1.05 or so salinity (I have an RO system), over the top of sand on both sides.
<SG 1.005 upwards to seawater is fine; 1.05 would be hypersaline and deadly!>
Use small internal power filter and guarded 50 watt or smaller heater ( although I'm going to bet it isn't going to go on much).
<Would highly recommend an external heater to avoid problems with mudskippers climbing onto a glass heater and scalding themselves. Failing that, make sure there's a plastic guard around the heater. But seriously, undertank heaters similar to those used for amphibian set-ups would be better. Filtration is relatively unimportant to mudskippers because they spend so little time underwater, so use whatever suits your budget.>
Aquascape with some large flat rocks, coral pieces, shells, and driftwood (a little!). Cover with bullet proof plastic (I don't expect it to get shot, but it doesn't warp.) Cycle.
<Always a good idea cycling the tank before putting in fish, but funnily enough Mudskippers are ammonia-tolerant "right out the box", presumably so they can survive in their wet burrows while the tide is out. They also spend most of their time on land, so aren't exposed to the ammonia anything like as much as regular fish. So provided you did lots of water changes so the ammonia stayed below 0.5 mg/l, you could probably cycle with the Mudskippers.>
Add quarantined (? number of mudskippers (P. kalolo) and fiddlers (and ?).
<Richard isn't a fan of mixing crabs and Mudskippers, so be careful here. Big crabs will nip small Mudskippers, and big Mudskippers will eat small crabs. Fiddlers are probably the best crabs to go with because they're deposit feeders rather than omnivores, but be careful. Periophthalmus kalolo is a fairly aggressive species, so either avoid having more than one male or else overstock the tank so no single male becomes hyperdominant.>
Pull up a chair in front and watch!
<Sounds about right.>
So maybe my questions are apparent here.
1. I was told to plant the seeds in a gallon pot, I'm guessing clay. Is this a good size. I think the pots sound like a good idea given the root strength. What do you think of the gallon size and how many do you think I should do in a 40. The picture in the book (which is a 40) shows four , and I don't think the pots are that big. I was thinking 3?
<Mangroves are trees, so whatever you do with them and however you pot them, eventually they will get too big. I don't actually rate them highly for this sort of set up.>
2. What kind of sand? The book says silver, but I was thinking aragonite or even oolitic to keep pH high.
<Without undergravel filtration, the buffering effect of a mound of coral sand is limited. Buffering is proportional to the surface area of coral sand in contact with moving water; in the case of a layer of coral sand without undergravel filtration, only the top grains of sand are in contact with moving water. So I'd not fuss about this issue.>
3. What rock is safe? I think limestone would help the pH, but I think granite is the most common, in the yard sort of rock (I don't intend to buy it.) Is there rock I should NOT use? (Obviously nothing that would be too sharp on the fish.)
<Again, don't be too worried about the pH issue. Marine salt mix will buffer the water nicely, and if it doesn't, you can also add a bit of home-brew Malawi Salt mix to up the carbonate hardness. I've described this elsewhere on WWM:
http://www.wetwebmedia.com/FWSubWebindex/fwhardnessfaqs.htm
So choose rocks that look nice, aren't spiky or rough, and don't have metallic seams in them that might poison the fish/crabs.>
4. I know driftwood is acidic, do you think the other stuff would out weigh it? Do I need to add something for hardness, pH? I have B-Ionic. I was thinking though that that was a bit overkill.
<Bogwood will have minimal effect. If it does, up the carbonate hardness as stated above.>
5. Stocking number? (mudskippers, crabs). Any safe critter to put in there. I am guessing I don't have room for much.
<Mudskippers are funny about tankmates. Your best bets are things like small brackish water livebearers, perhaps Guppies or Limia. But big Mudskippers will eat small fish, while big fish terrify Mudskippers who view them as predators.>
6. Cycling? I have read not such good things about BioSpira, that it isn't refrigerated. I have never seen it refrigerated. Fish food? Shrimp?
<Any of the above. Or just let nature take its course, using the Mudskippers or crabs.>
7. I live in the desert, should I think about a fog maker, to get up the humidity a bit?
<The lid on the tank should take care of this automatically.>
OK, I think that's enough. I was working on brevity.
Thanks Crew!!! You are terrific!
--des
<Hope this helps, Neale.>

Re: Mangrove "swamp"/ mudskipper, fiddler tank? 7/31/08
Hi Neale,
Thanks for the great information.
<Would highly recommend looking over Richard Mleczko's chapter on mudskippers in my 'Brackish-Water Fishes' book. He's easily the world expert on keeping these fish in captivity, and Just ordered off Amazon.
<>
> <Do make sure the tank is "mudskipper-proof", as these fish will climb out of any gaps they find.>
Yes, I have kept Jawfish. Tricky little devils. Fortunately mudskippers aren't $180 like those cool blue spotted Jawfish. Just when I thought it was safe to remove the netting around filters and the like, he jumped to his death! So no more removing netting, though without hang on the back stuff should be easier really-- until trees grow.
<<Ah, seems you're mentally prepared at least! The difference is that Mudskippers are gobies, and are equipped with a neat suction cup that lets them climb up vertical surfaces, including glass.>>
<Mangroves grow very slowly, and you may find plastic plants or houseplants in plastic pots (to keep the salty water out) will work at least as well. Plants like Philodendron work very well for this sort of thing.>
The way I read Scott's book, it was the ceramic pots and not the actual trees that kept the bank up (along with rock. So you are really not depending on tree growth.
<<I have the book and checked. My issue with ceramic pots is they're porous, so will let salt in. If you're growing salt-tolerant plants like mangroves or Nypa palms or whatever, then use whatever pots you want.>>
> <SG 1.005 upwards to seawater is fine; 1.05 would be hypersaline and deadly!>
Oh yes, woops! It's not a typo really, but I am familiar with all this. Just will have to go through the numbers again.
<<Good.>>
Thanks for advise on filtration and heaters!
>below 0.5 mg/l, you could probably cycle with the Mudskippers.>
Cycle with fish! Yikes! This is new info and I have never seen this (though saw they were tolerant of ammonia.
<<Some mudskippers will happily frolic around sewage outfall pipes. They are incredibly tough fish.>>
What about quarantining these guys (gals)? I have a ten gal QT. I was thinking in terms of about 2-4 inches of water and some rocks (or maybe dinner plates.
<<Since they're the only fish in the tank, quarantining them is redundant. Of course you can't use formalin or copper medications in a system with crabs, but brackish water will kill off Whitespot anyway.>>
> Periophthalmus kalolo is a fairly aggressive species, so either avoid having more than one male or else overstock the tank so no single male becomes hyperdominant.>
What's your definition of overstock of P. kalolo in a 40?
<<Depends on the size of the fish, and how much land there is. Richard's basic idea is that if all the fish are crammed onto the same bogwood branch or sand bank, none of them can make a territory. I'd be looking at half a dozen specimens, at least.>>
Or can you sex the fish to determine which is male?
<<Difficult to sex Periophthalmus spp. except to say males are more aggressive!>>
Also I was told to overstock the crabs. Both because they are aggressive, and because some will be eaten-- this from a guy who does barbarus which are even nastier.
<<P. barbarus usually ends up being kept alone.>>
> http://www.wetwebmedia.com/FWSubWebindex/fwhardnessfaqs.htm
Thanks for the link.
> <Hope this helps, Neale.>
You're all great!
<<We do try.>>
--des
<<Cheers, Neale.>>

Fiddler crab not moving, feared dead. 3/6/08
Greetings Crew!
I have a brackish tank with 4 Fiddler crabs (3 until yesterday, when I rescued another from PetSmart) I have had 2 of the crabs, a female and male, for longer than a year with everything ok. However, I woke up this morning to find the older female back-down with legs in the air...er, water, and not moving. I got her out, moved her around, tried to provoke a response, but nothing. I don't want to get rid of her for fear she may be molting, but if she is dead and I leave her in she will foul the tank. She has been this way for over 12 hours. Thanks for your help.
Phillip
<Hello Phillip. Sounds as if she is dead. Even when moulting, crabs have mobile mouthparts and gills. So if nothing is moving at all on your crab, she's probably dead. There's some reports that Iodine is a critical supplement that needs to be added to aquaria for crustaceans to do well in the long term. It's an inexpensive addition you can buy from any store catering for marine aquarists. Certainly worth a shot to see if that improves things with the remaining crabs. Do also bear in mind that Uca species only live for about 18 months in the wild, so anything beyond that in the aquarium is a bonus. Cheers, Neale.>

My crab isn't moving, BR 1/1/08
Hello crew,
<Greetings and happy new year!>
I was wondering if you would be able to help me out. I have a crab (*Seserama bidens*), sold to me as a Red Claw Crab.
<Ah yes... now known as Perisesarma bidens, though the red-claw crabs traded may be multiple species, given that Perisesarma bidens is primarily from East Asia while most exports are from Southeast Asia and elsewhere.>
I bought it close on a month ago and he quickly became my favourite addition, roaming about searching for food and generally acting in a brazen manner.
<Quite so. These are rewarding pets when cared for properly, and well worth their own specialised quarters.>
However, I recently purchased a 30 gallon tank filled 2/3, bogwood creating a land area and a rock pile for my two crabs to hide in (the other being a golden fiddler (*Uca *sp.) ) and for my dragon goby (*Gobioides broussonetti*).
<A nice collection of livestock.>
The new tank seems healthy (specific gravity at 1.005).
that's the only real thing I measure) the guppies and platys that share it with them are doing fine, and the fiddler is quite lively. Crushed coral for substrate, java fern floating around, trying to get some pieces to take root.
<All sounds fine, though strictly speaking Platies aren't brackish water fish, though my experiences agree with yours that they do well at low salinities.>
The problem is the red claw, who used to be quite active, scavenging around his log as well as in the water, recently took to hiding. I assumed it was just molting, and after maybe three days, and no actual result, I picked out the rock he'd been holding on to from the rocky pile as he had not been eating or moving and I feared the dragon, who also likes that spot, might stress him out.
<Curious. I'd have associated hiding behaviour with moulting, too. Crabs of most sorts are potentially antagonistic towards one another, so do check there isn't bullying between the Perisesarma and Uca crabs.>
He looked just as he always did, no colour change, nothing that would indicate molting to me. As I have mentioned he used to spend a good bit of time on land, I thought maybe he just couldn't get up there now (he'd been missing a leg upon purchase, I know it's a no-no, but he was the only one left, and I hadn't really noticed till I got him home).
<A missing leg usually isn't a problem when these crabs; they're quite tough and regenerate lost limbs quickly when kept in brackish water. On the other hand, our ability to prevent secondary infections in invertebrates isn't good, given that things like copper are toxic to crustaceans even at very low doses.>
So I slipped him onto the wood and sprinkled a few bloodworms in front of him, he stayed for a while and then crawled off and fell into the water where he landed upside down. Despite much flailing he was unable to right himself, so I stuck the net in and he quickly righted himself. He's been there in the open, next to a large shell for over a day, not really moving and I still haven't noticed him eating. He's not being bothered by any of his neighbours. What do you suppose is wrong with him?
<Very difficult to say. One problem with these crabs is they're often traded as freshwater animals, and if they've been kept in freshwater at the wholesaler and the retailer, then they can lose condition. Uca crabs are much worse in this regard than Perisesarma, but it is still one more factor beyond the aquarist's control. We don't really know anything much about secondary infections or parasites of crabs. Pretty much they're either healthy or dying. If yours is going to recover, it will, but otherwise the best you can do is watch, keep the water clean, provide suitable food, and if the crab dies, remove it at once.>
My mother keeps telling me he's dead, and I try to tell her he's just molting, do you suppose this is so? He'd often sit for a while not moving before hand, but never for days! I don't really know what's typical molting behavior for crabs, I'd always thought they hid away after they molted, or during, not beforehand.
<Moulting is very obvious and usually over in a couple of days. One problem with crabs and indeed freshwater crustaceans generally is iodine. While small shrimps seem to get enough iodine out of the water or their food, larger animals like crayfish and crabs apparently benefit from iodine supplements. These supplements can be purchased from stores catering to marine aquarists as iodine supplements are widely used in reef tanks. At this point it might be too late for the red-claw crab, but any new specimens you buy, and the Uca crab as well, will benefit.>
I wouldn't think it would be a problem with my levels, as the fiddler and everyone else are doing fine. I heard a rumor of Java ferns being poisonous to fish, he ate a good chunk of one before I moved them, could that be a factor?
<Possible, though normally animals stop eating the Java ferns because they taste nasty long before they actually get sick.>
I'm just trying to think of everything here, no matter how absurd. I apologize for my lengthiness, but the instructions on your site said include every detail.
Any thoughts would be well appreciated,
-Collin
<Hope this helps, Neale.>

Re: BR crabs... Now: Specific Gravity 1.010... for Hermits, Dragon Goby... 1/2/08
Hello there,
<Hello Collin,>
I wrote in yesterday about a crab who's not up to his norm, and I will for sure be trying to track down an iodine supplement (as recommended by Neale) to help out at this stage, whatever good that will do. I had heard about this, but there is a slight lack of aquarists specializing in crustaceans or BW tanks in my area and I couldn't find anything locally on it, but I know of one place that probably has it and knows what they're at.
<Anywhere specialising in reef tanks should have this, and failing that, you could obtain online.>
But! I have another question:
I read on your site that the blue-legged hermit crab (Clibanarius tricolor) could be acclimatized to a specific gravity of 1.010
<Apparently so. Do acclimate them carefully, and take great care to identify the crabs carefully before sticking them in a low-salinity environment. SG 1.010 is at the low end of their range, and you will of course need to make sure other things like water quality are "marine standard".>
I was wondering if you could tell me if the inhabitants of my brackish tank would be fine with this level of salt, as my findings on the internet have been rather inconclusive with different authors throwing numbers around as if they were just that: numbers. There doesn't seem to be any set specific gravity that people can rely on for these animals.
<Uca and Perisesarma should be fine; both spend minimal time in the water and likely breed in the sea anyway. If you're concerned, put a small basin of plain freshwater for them to drink somewhere on the land. An upturned Oyster shell stuck in the sand would be ideal. Guppies can be acclimated to anything up to full strength seawater safely, but you must do this very slowly, over several weeks. You can actually buy "marine guppies" as feeders for marine fish. The Dragon goby will be very happy at SG 1.010. The only chap who can't be kept there is the Platy.>
Anywho, my tank has a golden fiddler (*Uca *sp.), dragon goby (*Gobioides broussonetti*), Red claw crab (Perisesarma bidens), two guppies and two platys. So I was wondering if you would be able to tell me if I would be able to house this little guy sometime in the near future with the current inhabitants, maybe rehousing the guppies and platys? Also, would I be able to add the hermit with the current bottom dwellers that are on the go in there given this is all a 29 gallon tank? I may be short one red claw crab within the next week or two, if that's a factor. (Given his current condition.

Though I was watching him "scratch" his claws off one another, and against his legs. I know the fiddler and red claw both came from the same tank, same store, only the red claw had been in there about a month later till I bought him, I hadn't really been counting. Could have been FW, I wouldn't be surprised, I'll ask them soon.)
<Usually these things are sold as freshwater.>
So yeah, thanks in advance for reading my email,
You guys are awesome
-Collin
<Glad we could help. Cheers, Neale.>

Clibanarius tricolor biotype 1/14/07
Hello Robert,
<Neale>
I can probably rustle up a few pictures. There are also some useful sources on Wikipedia, which we used in my book (which I finally have a preview copy of, by the way). So there's other options, too.
<Have the ones you sent along, thanks. Will post with credit to you>
Since you're a marine guy, perhaps you'll know whether the blue-leg hermit sold in the UK (Clibanarius tricolor) is the same as the one in the US. I've mentioned it in the article because it does well down to SG 1.010. I assume it's a rocky shore or estuarine species that gets collected as a cheap reef critter. But I don't know anything specific about its ecology. Can you enlighten?

Cheers, Neale
<BobF, out in HI... trying to catch up!>

Fiddler Crabs 12/14/06
My son brought two fiddler crabs home from school after a class project. We have tried to learn about them from internet searches, but only recently found your web site. It has some great information!
<Ah, good... We intend to be useful (timely, accurate, significant, meaningful... in our information presentation... And always open to review, suggestions for improvement>
We've set up a small tank with aquarium gravel, and we set a 3/4" deep dish (actually the bottom of an old pencil case) in the center. We've added some plastic plants and a small aquarium feature, which the crabs seems to like to hide under. We keep gravel and brackish water in the dish. We feed them ground hermit crab pellets, bits of krill, and bits of cuttlefish bone. I remove approx. 1/5 of the water every night and replace it with fresh, and clean the tank every two weeks.
<Sounds very good>
We've had the crabs two months. At first they were very active, scurrying around the stones at night. Now they seem to spend all their time in the water, hiding under the tank features.
<Mmm, not atypical behavior. Are shy animals that don't like a lot of "commotion">
They became active again a few days ago when I cleaned the tank, but soon went into hiding again. In the time we've had them, they have not molted.
<Will do so in time... with growth>
Does this sound like normal behavior?
<Not unusual thus far>
Is there something more we should be doing?
<Do you know, have you tried to find out the name of the species you have? Some fiddlers have quite different requirements... e.g. the saltiness of their water...>
We really like the little guys and want to take good care of them. I'm not prepared to invest a lot of money in equipment, but would at least like to know what I should be doing.
Thank you for your help!
Mary
<Please consider setting your child on the task of discovering the species involved here... And write me/us back re your progress. Bob Fenner>

Re: Fiddler Crabs 12/15/06
Thank you! I will share your reply with my son and set him upon his research task!
Mary
<Ah, good. BobF>

Dismembered crab 11/28/06
I suspect this question will end up being mostly academic because I have a feeling the critter in question will be an ex-critter by the time I get home. I've got two red claw crabs
<Likely Fiddlers, Uca>
in a 25 gal. brackish tank that had, up until last night, coexisted just fine. They had established separate territories and mostly didn't interact at all. Well, I added some new plants last night and this morning awoke to a crab devoid of its pinchers. Completely amputated cleanly at the joint with the body.
It was flailing around upside down and couldn't right itself. I moved it back up to its territory and placed it somewhere where it was hidden and mostly upright.
As I said, I'll be surprised if it survives the shock, but if it does, is there anything I can do to help it survive until it molts and starts to get its front claws back?
<Separate it from the other conspecific crab>
I know that those claws are what it uses mainly to feed itself and it doesn't seem to have alternative legs that it uses like our crayfish do. And would adding something like Melafix make any difference?
<No to adding this or any other phony or real medicine... time, feeding, keeping the water quality constant... When the crab molts a few times, it will re-generate its missing limbs. Bob Fenner>
Sarah

Re: Dismembered crab 11/28/06
Thanks for the suggestions. And no, it's not a fiddler, it's a red claw crab, Sesarma bidens or whatever they've changed the taxonomy to.
Sarah
<Ahh, thank you for this. My input remains the same. Bob Fenner>

Brackish Fish and Crabs - 3/5/2006
I am very interested in having brackish crabs and brackish fish. I have not bought a decent sized tank yet but I want to research types of fish first. I like puffers (who doesn't) but obviously, they cannot go with crabs and the like.
<<Depends on the personality of the puffer, but you are right, as a rule.>>
I have gone on very many internet sites and they sometimes have information on brackish crabs and fish in the same tank, but only ever say top dwelling fish and short finned fish. One of the only examples of brackish fish and crabs was red claw crabs and bumblebee gobies but those are bottom dwelling! If possible, could I be told of all possible combinations of fish and crabs (in brackish conditions) including more than one type of fish to one type of crab?
<<Too many variables, you are going to have to do your own research here.>>
I like red claw crabs but would go for another like fiddlers. I would only aim at having one or two crabs in a tank. To make a more specific analysis of what type of tank I am after I would have to say an around 50-gallon tank with a lot of depth and width (not much of a tall tank person). For internal decoration and design, I would like to have a fake rock cave with its entrance facing the front of the tank so I can still see the crabs inside (maybe logs so they can reach the air not sure yet on what add so they can reach)
<<Do make sure you house the crabs you choose properly, and create a dry land area, if necessary.>>
I would really like to know some names at least of some top dwelling short finned brackish fish. If there are no good combinations, if possible, could I be sent a table or something in which it shows what brackish fish can go with what?
<<No such table exists, sorry!>>
This is a lot to ask but it would be extremely helpful and I may have asked things against your policies (apologies if I have) but I saw that I had to type properly and I hope I did so adequately.
<<Capitalized I’s would be nice too.>>
I will not expect a question this long to get a full reply instantly and I do hope this is a free service otherwise oops.
<<It is, yes.>>
Yours sincerely and thankfully whether I get the things I asked for or not (very long message to read),
James Briscoe
<<Look into Orange Chromides; they are a beautiful low-end brackish Cichlid. Good luck with your research. Lisa.>>

Marine Inverts in Brackish Aquaria? - 01/03/2006
I've looked all over the web on this question.
<All of it? It's a big place.>
So ya'll are my last hope on this one.
<I'll see what I can do Obi-Won...I mean Michael.>
I have a light brackish 29 gallon with an Archer and a Leopard Puffer. My question is can I buy a saltwater crab and acclimate it to my tank.
<Generally speaking; no. Reef Invertebrates come from one of the most stable environments and can not adapt to such a change.>
I am willing to increase my salinity, if need be.
<Research WWM re: the proper environment for marine inverts.>
I know puffers eat crabs and snails, however mine is pretty small and well fed with lots of cover in tank for hiding.
<You'd be surprised how much damage that little beak can do.>
Maybe a larger crab or hermit?
<See above.>
Thanks, Michael
<Welcome, Adam J.>

Crabs & Puffer? 5/31/05
Howdy,
<Hi, Pufferpunk here>
I am wanting to add a brackish water crab that can stay in the water all the time in my 10 gallon tank.
A blue legged crab was a thought, but I'm not sure he can stay in brackish water. The other part of the
problem is that I have a figure 8 puffer in there too. I'm thinking the puffer will eat a blue legged crab
even if he could survive the water conditions. I've read plenty of websites that just say nothing can go
in with the puffer (crabs and other cleaners that stir up the sand). For a small tank with only 1 fish, I
wanted some other small creatures to climb on the liverock and stuff. Needless to say, snails are out
of the question. Any suggestions?
<Crabs & snails are puffer food. I don't suggest adding anything a puffer can eat. There really is no clean-up crew for that tank, you'll have to do your own maid service. In a 10g, it is best to keep the puffer alone (interesting enough tank w/just the puffer) but you might be able to get away with a couple of bumblebee gobies as tank mates. They may get eaten though, if that is the kind of F8 you have. You just can't tell with a puffer! ~PP>
Thanks, Brian

Fiddler Crabs on the Lam!
I had 2 fiddler crabs, both tried to escape the tank, one did.
<Yes, they are great escape artists. Best to keep the water level down a couple of inches & keep a tight fitting lid on top, taping off any entrance for cords, etc, where they can climb to get out.>
I have read that they sometimes require time away from water but must be kept moist. I have mine in a deep 40g. tank, how often should I remove him and for how long should I keep him out of the water? Does this require a separate tank?
<A floating piece of driftwood or plant should suffice.>
I have only had these for about two weeks but would like to keep the one I have left, and hopefully from escaping! I still haven't found the other one!

Red Claw Crab
<Hi Anthony, MacL here. The only red claw crab I know of is actually a brackish crab often sold for freshwater. Is this what you have?> I purchased a red claw crab from a local Fish store about 2 weeks ago. I believe the crab is a female due to the very small claws. Anyway, recently she has had her abdomen hanging open. <Maybe releasing eggs?> I figure she was getting ready to molt, but she hasn't done anything for 2 days now.
She has already molted once since we have had her and it didn't take long. She has plenty of different kinds of food. Also these past 2 days she is flipping herself over on her back. <Not a really good sign.> Can you tell me what is wrong? <I'm just guessing here but I think you probably have her in fresh water and she needs some salt. I also think it might be a difference in PH as well.> I have searched through the internet, but cannot find any information on Red Claw Crabs. Thank you for your time and patience. <Anthony you might do the research on them and decide if it needs to be in brackish water or not and make a decision from there.>
Anthony <An excellent site re this species: http://wrongcrowd.com/aquaria/crab/ RMF>

Rogue Crab
>Hey WWM crew.
>>Hi.
>I have a slight problem.
>>Me too, but I'm not going to talk about it right now.
>My red clawed crab has decided to take a walk on the dry side of the tank.
>>The "dry side"? As in "the outside"?
>I have spent two days looking and am at a loss as to where it is.
>>What kind of crab is this, exactly? A land hermit crab? A saltwater hermit crab? A freshwater fiddler crab? Is it a tasty crab, maybe?
>Two questions. Will it still be alive this long outside the tank?
>>I have no idea, since there are so many crabs we can be talking about, here. If it's a land hermit, and you're keeping it in a tank with NO dry areas, then it's off to find a new flat, better digs and all that. Otherwise..
>And if so, how in the HELL do I track the little bastard down???
>>Find a sexy girl crab, maybe?
>I'd like to find him before the cats do, and if he's perished I'd really rather not find him by smell.
>>What if the cats already found him, and that's why you can't?
>Any help you can pass along would be greatly appreciated. Thanks, Keith P.S. Don't tell my wife.....
>>Mum's the word! I'd start checking the kitty dumplings, myself. Marina

Rogue Crabby FOUND!
>Dear crew, Crab found!!!
>>Hee! Great. And don't say I spilled the beans to your wife!
>More importantly, ALIVE!!! Apparently it had been living in the power filter for the last week...
>>Must like it there.
>So now, what do I do with it?
>>Scold it.
>It's not a hermit, but I don't know much more about it than that. It was sold to me as a "red clawed crab," I didn't read the scientific name. Didn't think I'd need to. Best descript. I can give is that it's about 3/4" across the back, and is shaped like a big brown Chiclet (gum), with arms and legs. It has darker brown patterning over a lighter shell, with two big red pinchers up front that are white on the tips. And it's freshwater.
>>That's somewhat helpful.
>I've offered meaty foods, but it's never showed much interest. Could it be wanting algae, or just anything that's decaying enough to be tasty?
>>That may be, or it's also wanting a private flat, a room of his own so to speak. If you don't mind it being in the filter, leave it there. If you do, then give it a hole to call home, and don't worry about feeding it directly at this point. You could try a few things, but let's try that first, see if it's happier having some privacy. When you scold it, don't wag your finger too close to those claws. Marina
>As always, any help is welcome. Keith

Rogue Crab goes to the Rogue's Gallery
>Hey Marina, a parting note on my eight legged headache.
>>I suppose he's too small of a bit of meat to be enjoyed that way, eh?
>After much searching, I have a solid I.D., and another "fish experiment" to irritate the wife with. (Not to say she doesn't enjoy the tanks I have, she's even encouraging a saltwater project. But, She IS jealous of the time it takes
to care for, and more importantly view them. And the only reason she wants marine is because she wants, and I quote, "Nemo fish." <sigh>)
>>Oh lord, not Nemo again! (A tip, they do NOT need anemones!)
>I have discovered myself to be the proud owner of one Sesarma bidens.
>>A who? If you can possibly send in some decent pictures, we'd love to have them archived on the site.
>A fresh to brackish species from southeast Asia.
>>Ah!
>Eats anything handy, as long as it's not moving.
>>Thank goodness for that, and other small favors.
>Not known for chasing fish, fortunately. Likes to trek out on dry land a few hours a day.
>>So he might appreciate something more resembling a vivarium, or mangrove setup.
>Smart, strong, fast, and hardy apparently makes for a notorious escape artist. But, at least I know why my filter cartridge lasted twice as long as normal, he cleaned it for me... Go figure. Looks like I'm entering the world of <GASP> species tanks!
>>Sounds like every filter needs one of these guys.
>As if my life wasn't interesting enough. Oh well, something new for the kids to poke at. Keith
>>I like the way you think. Glad to know you've nailed him down, so to speak. And thanks for the follow-up. Marina

Brackish Arthropods and Catfish 7/11/03
What kind or kinds of crabs can live in a brackish water aquarium?
<quite a few shrimp and crabs.. some of which are seen in the trade like ghost/grass shrimp, mangrove and fiddler crabs... none of which are compatible with your puffer which will pick their eyes out if not eat them outright>
I currently have a 65 gallon tank with bumble bee gobies, green scats, puffers, and mollies. My tank has a sand bottom that needs some house cleaning. Got any ideas? S/y, Carole
<The is an Albina (not "albino") Pleco that is brackish tolerant. A good scavenger and innocuous. Ships out of South America:
http://amazingrays.50megs.com/custom2.html
Best regards, Anthony>

Feeding (freshwater crab)
I just got an aquarium, my first fish was the classic gold fish
I just got two more fish and a crab, am not sure what kind but its small and has one big claw and one very small, <<Sounds like a fiddler crab, and depending which type you have may be better off in a brackish system.>> my question is am not sure what or how to feed it, I was told the shrimp pellets but it doesn't seem interested, am not sure if that's what I should be trying to feed it and if it would eat them after a while when I left it would never get a chance because the (small white fish with orange on its head) eats all the food as soon as it hits the tank <<Hmmm... most crabs are termed opportunistic omnivores, which means they'll eat just about anything they can get their claws on, which sometimes included each other, depending on the type of crab. I would ask the place where you got the crab what the Latin name is, hopefully on their shipping list, and use that to find more information about this crab. In the mean while, here is a URL to get you started: http://www.wetwebmedia.com/BrackishSubWebIndex/braccrabs.htm - and do read the FAQs beyond. Cheers, J -- >>

hi (Collected brackish crabs...)
<<Hello...>>
my name is Samantha. <<Mine is Jason - how are you?>> I went crabbing the other day and all the crabs we caught were to small to keep. when we got home my little sister asked how long does it take for a crab to grow an inch. I told her I' find out for her . so if you could please e-mail me that would be great. bye
Samantha
<<You sure asked the tough question... for starters, crabs and their other cousins in the Arthropoda family actually shed their skin in order to grow in a process called molting. So... the real answer to your question is: It depends on how often the crab molts. This can be once every couple of weeks to once a month or once every couple of months depending on the type of crab. Even then not all crabs grow to large sizes, some stay small. If you want to read up some more on crabs, here are a couple of links:
http://www.wetwebmedia.com/marine/inverts/arthropoda/crabs/swcrabs.htm
http://www.wetwebmedia.com/BrackishSubWebIndex/braccrabs.htm
Hope that is helpful. Cheers, J -- >>

"A Craw-Fish by any other Name would Chew Plants..."
Mr. Fenner:
I am in the early stages of preparation for building my first community tank. I am planning a 35-Gal tank with many live plants and two species of schooling middle fish, one species of surface fish, and an additional species of bottom-feeding/Pleco-type fish. Is this feasible?
<Sure>
My main concern is this: I feel that in the future I may be unable to defend myself against the irresistible charms of lobsters and crayfish.
<They are delicious... prepared properly!>
Is there a place in a perfectly harmonic community tank for one of these invertebrates?
<Mmm, no, not really. There are some fresh to brackish crustaceans that are "better"... please read: http://www.wetwebmedia.com/shrimpfw.htm>
I hear that they have picky tastes in water pH and temperature, are destructive to aquatic landscaping, and can be determined to bust out and go AWOL. Is there a way to have fish AND Yabbies?
<Again... not really... their tastes are actually "too cosmopolitan", and many species are known to be quite "eury" condition... adaptable to widely varying conditions... but most all what folks call "lobsters", crayfish, crawdads, ditch "bugs"... are all too destructive, fish-eating to be "harmonious" in a community tank... Maybe two tanks? Bob Fenner>
Please advise.

Freshwater crabs
Hello,
I want to try keeping freshwater tropical crabs. The species that is often on sale in the UK, small red crabs. I can't find any books or articles on keeping them. I would like to know;
1. what they like to eat,
2. how many to a tank,
3. if I can keep a few fish with them as well,
4. how long they live,
5. what sort of tank (plants, rocks, shelter, etc),
6. ph of the water,
7. filtration,
8. how much oxygen,
9. and how simple they are to look after.
Thank you
<Hmm, I suspect it is Sesarma bidens you are referring to. Please start with this site: http://wrongcrowd.com/~aquaria/crab/
and use your search engine with the common and scientific names to find more. Some general husbandry information can also be found on our site: http://wetwebmedia.com/brcrabs.htm
Be chatting, Bob Fenner>

I just got from our pet store tiny red claw crab now I cannot find out much
about them & how to care for them they are not hermit crabs but red crabs I looked up res Caribbean crabs found nothing I need to know more what they need thanks
Sharon
>>
Not enough information, I'm afraid. Maybe call, go back to the store, and ask them to check their invoice for the scientific name of these decapod crustaceans... And do keep your eye on the crab... Some get quite big, and many are opportunistic... eaters of other livestock they can get their claws on
Bob Fenner

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