It would be sweet if they threw in some "Legendary" fish. Like in some games they have super rare resources, they could have a few super rare fish.
And when you catch said fish, it would become your permanent pet. Doing everything you command it to do. And not just the usual lame pet commands like follow/attack. I'm talking commands like "massage", which would give you a "relaxed" buff, making your fishing much more fruitful. Or "sing", where your fish would sing to you giving you the buff "at ease", making your fishing even better. And it doesn't stop at just self buffs. You can command Rufus(you can name your fish) to buff your friends too. "Foot Massage" would buff your friends speed.
Or how about breeding fish? You could catch a few fish and make them breed, thus producing infinite amounts of fish. And after a few hundred fish, you could buy your own pond, toss them in, and charge people to fish there. Profit!
And the most coveted fish of all, the AttackFish. A fish that would help you out in battle. But mostly in water battles. On land battes he would have his damage reduced 90%, because you would bring the beast out and he would just flop around. But in water he could swim around and bite the absolute **** out of that dodo you lured into the puddle.