Crabbies

[Pythonian]

hey guys i don't even deserve to be on this forum .. i have a 10g tank with one goldfish (gold) and another goldfish (that is black with bulging eyes) hehe.. but i love them to death! (names are paco and pedro). so i'm not like a breeder or anything just a kid with pets anyway. I have 2 land hermit crabs too (iccus and oblina :-D ) and i want aquatic ones:
A. are they freshwater?
B. Can they live with the my goldfish
and C. where can i find them?? THank u

Mike