We stopped at this restaurant for dinner on the way to the airport. They are licensed to serve specialty dishes from the Amazon, such as Cayman, turtle and rays. They have a buffet with a few dishes of each kind of meat, as well as some other typical north Brazilian dishes. The price is about 60 reais per person, not including drinks but with a small selection of desserts.
It's worth to try for the different kinds of food. The quality of the food is ok, but nothing spectacular.