New big fish, is there any useful ?

Since the trailer doesn't say anything but just "Catch big fish" (no even animation of the actual fish either).

I wonder if any fisher here catch them? Also, does it provide any useful other than achievement? For example, can sell in market for high price? Need in culinary 3 star recipe? or how much price NPC offer them.

Looking at the fish list in the XVI database site, none of them seem to be for anything except the Silver Sovereign for getting that rod.

So still useless it seems, I'll still fish them for the sake of completion, but profit is still not something fisherman is for.

The Navigator's Brand and Silver Sovereign can not be sold but so far the rest of the big fish can be. Giant catfish got a spot in some cooking ingredients but it's not a new fish.