Hermit Crab info

Hey there looking for some information on hermit crabs. I have one in my salt water tank and my LFS guy said their different than the hermit crabs that live outside of water. So my question is does anyone know a good thread on them or a website that can tell me info on saltwater hermit crabs?

Questions I am looking for...
What do they eat?
Can they live off fish food?
My Hermit crab used to be very active now her picks a spot on my rock and sits there for a couple days?
How big do they get?
How fast do they grow?
How long do they live?
Can they survive with just eating off my live rock?

I also have about the same questions for my Astril snails

 

If you want a decent general information site, check out wetwebmedia.com. Here's the hermit crab link from them.

 

You will need to post a pic of the hermit because they vary in size by species. They are opportunistic omnivores generally. They can range in size from 1" to over a foot at adult size.

Astrea snails are herbivores and grow to about an inch in diameter.

Do a search on the web for salt water hermits crabs you should find yours among the ones that will be shown.

 

Here he is

 

You have a blue knuckle hermit. It grows to 2".

Here is a link.
Electric Blue Knuckle Hermit Crab, Electric Blue Hermit Crab - Calcinus elegans

 

What's the name of the hermit crabs that can reach 1foot

 

Petrochirus diogenes. You need a very, very big tank for them.

 

Do you know the minimum gal?

 

Well it's not 6 LOL.

 

Well, consider that if it's a foot long, it needs at least a one foot by one foot area just to fit in without moving, then probably 6 feet by 6 feet to walk comfortably long term, with maybe a foot or two of water depth to keep submerged, at minimum. At two feet deep, that tank is over 500 gallons.

Then, the crab itself is gonna eat nearly anything it walks into, meaning no fish, corals or macroalgaes. Also no rock, and minimal sand, since the tank would then need to be deeper to accommodate that.