Here is a picture of it

Another special thing in this fish is that his spines are harder and thicker than normal, and it does look like pork ribs, wich is very interesting. This fish can also be found by the name of Pacu. Tambaqui can get up to 1 metre length, and up to 30 kilograms.
What you gonna need:
500 grams of Tambaqui ribs.
For the sauce
100 grams of fresh blueberries
10 ml of vinegar
15 grams of sugar
For the side
2 bananas
50 grams brazil nuts
Salt and pepper as you like.
Well, basically, these ribs are sautee. So all you need to do is add salt and pepper as you wish, and sautee the ribs slowly, so all the fat melts down n gets mixed inbetween the ribs.
The sauce is simple aswell. Add all the ingredients, maybe you will need some water. Leave it cooking untill all the berries melt in to the sauce.
The bananas are just plain grilled, no salt, no pepper.
Chop the nuts in small pieces, and then put them on heat, so they get cripy.