(Answer Quickly) How to care for crawfish as a pet?

I am getting a pet crawfish... i do not know how to care for it. I have a 5 gallon and 15 gallon tank from previous pets... which would be best? I already bought it and i need this info fast... What does it eat? What kind of tank is best? Fresh or Salt Water? Is a crawfish a good pet to have? Would it like friends, (more than 1 with it)? whoever answers all or most questions with the most detail will get 10 points of course and IF you gave excellent information, then on my all about me info thing i will put ``Be fan of ________ they are awesome and provide with best information. Thanks!'' Oh and do not report me if i do not do that because i will only give you a shout out if your reallly good! okk thankkss bye!