I am in that same situation actually. I have a 10 gallon in my basement that I can't use for fish because it leaks water from the bottom. I was thinking about hermit crabs but I will only get them when we vacation by the ocean. When you get them closer to where they are originally from they have always lasted longer for me. I wonder if it's because how they ship them. Anyway, hermit crabs are relatively easy to take care of as long as you follow certain rules. They can live up to 60 years, might I add, and grow as big as a baseball, but it takes forever. They are very intelligent. I had one the would come when I called its name. Their personalities have a very wide range though. Some are very shy, others are out-going, and some are just mean. I guess they are kind of like people in that way.
Because of the varity some don't get along well with others. But most do enjoy the company of their own kind. In the wild they live in packs of hundreds so getting acople together is a very good idea.
Just keep a eye on them to see if they get along. There have been some rare instances where one hermit would kill the other by eating him or ripping him apart, literally.
For the most part that doesn't happen however. If their is a sign of aggression one of the first things you'll notice is one hermit kicks the other out of his shell the the alpha crab moves in. But that isn't always the case because sometimes one crab decides he wants to move out on his own and the other just simply decided he liked the others shell better and moved in. Just like realistate.
If there is aggression you'll know by the way the two act around each other. Locking claws and such isn't a good thing. Hermies require heat and moisture, so a under tank heating pad must be provided as well as ''misting'' with the hand-held plastic spray jar. Spray their tanks once a day and spray them out side of the tank once a week. They will eat just about anything but they really like canned fishes, frozen shrimp (after it has thawed), and anything that would be laying around the sea shore in their natural habitat. All water that is put into their tank must be aged or dechloritized for the same reasons as fish. They can drawn easily so make surethat their water dishes are very shallow. Keep a tightly seeled wire mesh hood on the top of the tank because they can and will climb out while you are sleeping to explore the house. You could wake up the next morning, put on your shoes and find a sleeping hermy in it. Yes, it has happened to me.
Hermit crabs go through a molting stage every so often where they will burry themselves under the sand and change their skin. The process takes about 2 weeks on avaerage but its not that uncommon for it to take a month. For them to be able to molt you must have atleast 3'' of sand in your tank. More if you have a larger specimen. Molting is how the hermit is able to grow. Sometimes they will eat the extoskeleton, which is actually good for them, but other times they don't. Speaking of growing, as they grow bigger they will want to change shells. This means you must provide them with a varity of different sizes, shapes, and colors. Most seem to love a standard pearl colored twist shell. Don't ask me why. Some hermits change shells even if they haven't grown at all. Some hermits just like keepig busy. Hermit crabs do make noises, some do it more than others. People often describe it as a chirping or squeeking. Don't worry if yours doesn't make any noises, with some you may never hear them make noise the whole time you have them. You can use sand or gravel as a substrate. Some people say that sand is bad and makes it harder when they go under to molt. I've only kept sand every time I had hermies, and I only lost one this way. I've had sooo many of them for so many years I can't even keep track. Well, that's everything I can think of at the moment. If you have any more questions about hermit crabs, ask.
