Bettas and brackish
This question is threefold, but background first.
I have a two-year running planted tank with just about the easiest to grow plants in them (hornwort and Cabomba weeds) and a Betta (who is in heaven).  Ten gallons, inexpensive waterfall-type filtration turned all the way down to keep the water filtered but generally undisturbed at the surface, temperature at 82-84F, full spectrum lighting (as I pretty much used to use it as a plant-isolation tank to get the snails out of them... used to have a swarm of apple snails, which has since stabilized as the Betta tends to eat the egg sacs and young snails... basically anything he could fit in his mouth).  It was my first foray into plants and gave me the knowledge I needed to go into planting my goldfish tanks.
<Outstanding>
I am now interested in getting some (generally) bottom-dwelling small crabs, and according to the research I have done, while they can tolerate freshwater (poorly), they prefer brackish.
<Most of the species sold in the trade, yes>
I've done research into setting up a brackish system and I feel ready for it.  I've also been briefed in the requirements of the types of crabs I'm considering (but will eventually settle on a single pair of a single type, most likely the small red-clawed crabs) and feel ready to meet them.
<Okay>
Question one is:  Can the Betta tolerate a brackish or slightly-less-than-brackish salinity?  
<Yes... as can the hornwort/Ceratophyllum... but the Cabomba may well do its falling apart act>
I'd like to keep him (I got him as a fry and know he is around 19 months of age now) where he is, and possibly just slowly up the salinity to desired levels to get him used to it, as well as letting the microorganism population adapt to the change.
<Good technique>
Question two:  Would the Betta be socially compatible with these scavengers?  He generally will sleep on the plants and I've almost never seen him sleep on the gravel (I work nights, and keep the room dark on my nights off, so I have observed him during the 'night' part of his cycle).
<The Betta should not harm the crabs, but the reverse may well not be so... almost all crabs are opportunistic omnivores... and if hungry, might attack, consume the Betta>
Question three:  Answered on your brackish plants page, no, the plants will stick around.
Thank you,
Dan
<Be chatting, Bob Fenner>
 

Crabby Crab?  Sabrina Has Crab Envy! - 09/03/2005 Just bought an apparently Yellow Moon crab from the local garden centre.   <Research prior to purchase, next time....  I'm impressed, I suspect you have Geothelphusa albogilva.  This animal is currently unobtainable in the US.> Guy said it was ok in my tank with 3 goldfish which are very big.   <Likely untrue.> Got the heater for him and the right food etc.   <Goldfish are coldwater, shouldn't be heated.> He seems to want to get out of the tank all the time, life seems one big struggle to climb to the top and spend some quality time out of the water on top of the heater or filter system.   <Yup, this and all other crabs available in the freshwater hobby absolutely require a land mass with hiding space - these are land animals that spend some time in the water.  Geothelphusa albogilva is more terrestrial than anything.  At least the animal is actually freshwater.  I sure wish we got critters like that in the hobby in the US.> Can't find any info on these crabs <Not much out there, from a husbandry point of view - treat this like any other terrestrial semi-aquatic crab....  Give it a large land mass of several inches of sand and wood/leaf debris, with a great deal of cover/hiding and a few gallons of clean, circulating freshwater.> and worried I'm not looking after him right.  Can you give me any advice on making sure he has good quality of life?   <Just as above - this is an animal worth accommodating.> Would really appreciate your help and comments. <I'd absolutely LOVE some images of this animal.... please.... if you have time and a camera.  I have crab envy.> Kind regards,  Joanna <Wishing you and your new decapod well,  -Sabrina> Crabby Crab?  Sabrina Has Crab Envy! - II - 09/07/2005 God I feel so naive.....just thought I was buying a funny cute looking crab to live next to my computer and look nice.  Guess I was major uninformed. <No worries....  The fact that you are seeking information is wonderful.> Didn't realize I had something unusual! Please excuse my ignorance. <Again, no worries.> I am a total animal lover and now dead worried this poor little creature is not getting the right life. I will transfer him to another tank and somehow arrange land for him to rest on and water when he needs it. How come I can easily buy him here and you can't over there? <I have never heard of Geothelphusa offered for sale anywhere....  But Europe and the UK always tend to get "new" critters a few years prior to the US.  There are many shrimp and crabs available in Europe that I'd do a great deal to get my hands on!  I suppose I shall just remain patient....> I will take some pictures of him and send them to you... <Much appreciated!  I would very much like to see if this is in fact the crab I think it is.> again excuse my ignorance as a first time crab owner but what's the interest? He's not yellow or looks like he's from the moon haha, just a small baby crab that's whitish in colour and likes sitting on the heater.   <Once in a proper environment, I suspect you'll find him much more interesting.  The interest, to me, is that I have quite a passion/fascination with invertebrates, especially crabs and shrimp....  the interest with Geothelphusa, to me, is that they don't or shouldn't require saltwater access....  If there were more truely freshwater land crabs available in the hobby, folks would be more easily able to care for them properly, which is one of my main desires....> Guess I'm entering a whole new dimension I didn't know existed out there.   <Invertebrates are really amazing animals!> Would love to chat more, thanks for replying so quick.   <You bet.  Sorry for the delay in this response; I've been traveling a bit.> Where about in the US are you?   <In California....  In the Santa Cruz mountains.  Beautiful place.> I'm over in UK in Yorkshire - God's Country. <Sounds excellent!> Best regards,  Joanna <Wishing you and your crabby pal well,  -Sabrina>

Crabby Conversion? - 08/07/2005
Can saltwater crabs adapt to fresh water?
<Unfortunately, no.  Thanks for writing in!  -Sabrina>

Halloween Land Crab – 03/17/07
Hi, thank you for taking the time to read this.  I have what the pet store called a Halloween Land Crab.  
<Gercarcinus sp., maybe G. lateralis.>
He is not set up in some amazing aquarium, he is just in a plastic cage.  I have a water dish for him that's 2 inches deep that he climbs in and out of.  The bottom of the cage is filled with calcium sand and aquarium pebbles.  
<Ideally, he needs a sand substrate deep enough and just damp enough to burrow into, and needs enough saltwater and enough freshwater, each in separate containers, deep enough to fully submerge himself - though the land area is by far the most important.>
He has been doing really well eating bits of fruit such as apples, oranges, pineapple and also an occasional guppy.
<Needs more meaty foods, preferably things like human-consumption shrimp (raw, frozen and then thawed) and fish; krill, meaty fish foods, and also Nori (seaweed) would be other important foods.>
But recently three of his legs fell off on his right side!  What is going on?
<Likely he is very deficient in something that he needs - saltwater, perhaps, or iodine....  Feeding the foods mentioned above, especially shrimp, krill, and Nori which are rich in iodine, will be very important.  Supplementing the food with a reptile calcium supplement will be helpful, as well.>
He was not in a fight with another crab and I've never experienced him going through the "shedding process"! Is he unhappy or sick? How can I tell what's going on?
<sounds like a state of disease, not a normal molting situation at all....  I would urge you to improve this critter's living space and food.>
If this is below what you guys do, then I'm sorry to waste your time,
<A question is never a waste of time.>
I just need simple answers and can't seem to find them anywhere.
<Thank you very much for searching for your answers, and for asking questions.>
Nick
<All the best to you,  -Sabrina>