More questions about the hermit !?

I remember having hermit when i was a kid.i loved them because they were little as any little girl would, but there claws scared me half to death.i don't remember much but ill share what i remember.i don't remember feeding them anything.i think i just gave them water.i think your 15 gallon tank should be big enough.i think i had 3 hermit in a plastic cylinder cage once.it might have just been 2 though.i think they can do without salt water. sorry if i didn't answer much.i got a little lazy and didn't read everything.hope i was a little help.good luck.as for what i didn't answer, i don't know anything about that.maybe they're a little more work then i thought.....