I just thought I would point out that "langostino" or squat lobsters are strictly saltwater species. Petstore "freshwater lobsters" are always crayfish.
That's interesting. I had read that they were a type of crawfish, and freshwater. That was only one source, though... I guess I didn't do enough research. Looked it up on my phone in Rubios when we realized that what they were calling 'lobster tacos' seemed just like crawfish.