As with much of Marrakech, you face paying more if you are a visitor.
This is a bustling place, it's not immediately obvious if you're supposed to wait to be seated. We got a good spot near the street. The waiters were efficient, but our meals came at different times. I had finished my fish tagine before my wife's langoustines made an appearance. It all tasted great though.
Unfortunately they charged double for the langoustines. The fish is costed by weight, which is fine, but not if they pretend they have served you twice the amount you actually received. If you speak French and want to argue the toss, good luck. Otherwise don't bother - you can probably get just as good seafood at home, without the hassle.