Hello everyone, I'm interested in stocking my reef aquarium with some Electric Blue hermit Crabs. I'm curious as to what are everyone's thoughts on these little critters and also what are the benefits/downfalls of keeping them in my reef aquarium?

I love the Electric Blues. We had 3 in our tank at one point a couple of years ago, one of them is still alive and still growing (Flickr photoset (http://flickr.com/photos/drthompson/sets/72057594137460346/)), I'd estimate it's got to be around 5 years old now.

An important thing to keep in mind is that they get big (3 or 4 inches long, measured head to tail without a shell) and with a shell they're quite heavy. I watched one of ours puncture a Protopalythoa sp. polyp just by walking on it (their legs/feet are quite sharp) and they've dislodged many a frag that wasn't puttied/cemented in well enough, sending them spiraling into the substrate.

I think the electric blues (Calcinus elegans) are mostly from reefs around the Marshall Islands so I'd guess they're not as problematic in tanks stocked with predominantly large, branching stony coral species ... but they're so active and interesting to watch that I don't mind the odd frag or polyp getting trashed.

One last item, if there isn't enough "easy-to-get" food for them in your tank you'll probably want to (or need to) increase your snail budget ... our biggest electric blue once went through ~20 snails in 1 day when it couldn't find food ... they have no problem tearing snails off the glass/rocks and extracting them from their shells.

Doctorthompson, I went ahead and purchase 4 Electric Blue Hermit Crabs for my 40 gallon cube Reef Aquarium. They are extremely active and beautiful little critters. I'm curious about their growth as well as the reproduction.

Will they reproduce in our captive environments?
What should I provide for their growth and how and when should I know to provide it?
What foods do you feed your Electric Blue Hermit Crabs?
Any other pertinent information I should know about them?

Doctorthompson, On a side note I love the Gecko. My Girlfriend and I have on just like it.

Will they reproduce in our captive environments?

They certainly try! It took me a while to figure out what the weird "clack-clack" noises were that I used to hear in our tank ... it was 2 large shells, "banging" (ahem) against each other. I've never seen any hermit offspring in our tank though, of any species.

What should I provide for their growth and how and when should I know to provide it?

Lots of empty shells ranging from the same size the crabs currently use and progressing upwards in small increments. If your LFS charges an arm and a leg for empty shells (mine charges $1/shell for large shells) you can sometimes find bulk seashells at landscaping supply stores and garden centers (I found some around here for $3/pound of mixed shells).

What foods do you feed your Electric Blue Hermit Crabs?

If there isn't enough algae or edible detritus in the tank I just grab a strip of dried Nori, wet it, wrap it around a small chunk of rubble, and drop the wrapped rock into the tank near the crab ... but they'll pretty much eat anything. I've even seen ours pulling up and eating mats of cyanobacteria off the substrate.

Any other pertinent information I should know about them?

If you ever see them having trouble molting (ie. can't quite get out of the old "skin") try adding a tiny bit of iodine to the tank (no more than 1/3 or 1/4 of whatever dosage is recommended on the bottle) just after "lights-out" and check again in the morning. For some reason 2 of the 3 we got had occasional trouble molting in our tank for the first couple of months and I read that a slight iodine boost is supposed to help -- I know dosing iodine (in any amount, for any reason, and especially without a test kit) has historically been more of a hit-and-miss gamble than a solution, but it seemed to do the trick for our crabs.

Thank you for the information Doctorthompson. It is very much appreciated. I will post some photographs of the little critters today.

I have one and he is great! I love him. I have never had a problem with him hurting any of my soft/hard corals. A wonderful reef inhabitant in my mind.