Does the Na´vi fish?
 

One can wonder if the Na´vi catch some fish like creatures in the Oceans or in rivers and lakes? Also would be interesting to see what methods they use.

Also it would be interesting to learn about the aquatic fauna.

Perhaps we will learn about some of this in the sequels (especially if we will see more about the ocean).

In the CE deleted scene New Life, Neytiri was bow fishing in the river. So apparently there is some form of aquatic based fauna that is edible.

They fish, at least one way is by using arrows. The survival guide has detail on a few species of fish found on Pandora.

they sure do, they use spears and probably bow and arrows as well.

We will see a lot of Pandoran sealife in Avatar 2 I heard. I'm very curious :)

Its in the bonus content of them fishing as mentioned above on the deleted scene.

But I think it would be very cool to see Na'vi on a larger sea creature, like a whale out in the open ocean. And while one in in Tsaheylu with the whale the others fish for large fish on its back. Like what would be our Marlin or swordfish.

Yes they fish. The deleted scene "New Life" illustrates this. They use 3 pronged arrows and spears.