I want to get a sting ray in the next few months but I have some questions. Im new to fish keeping, but I have learned a lot in the last 2 months. I would like to get a 75 gallon tank, is this big enough. It is 18" deep. Also how difficult are these to keep alive, and what is a good price for one. I know they are expensive, but the aquarium by me wants 150 for one. Thanks