crazy fiddler crab

[saveme]

I just bought some new fish becuase my mother managed to kill all but one of my fish because she wouldn't wait for the water to warm up. anyway one of the two new fiddler crabs i bought keeps flipping over on it's back. we keep putting right and it just keeps doing it. plus it's lost it's big claw.

i purchased a tank heater and it seems to help with the flipping over thing but why does it do that and why did it lose it's claw plus will it grow it back? thank you

 

[Mumma.of.two]

Hi and welcome!
Fiddler crabs are brackish. They are not suited for FW tanks. They also require a land area and access to air. I'd suggest returning them or purchasing them their own tank.
Was your tank cycled?
http://www.aquariumadvice.com/forums/f15/guide-to-starting-a-freshwater-aquarium-186089.html
Please read this and if you have any questions don't be afraid to ask.