I still can't figure out how to catch those "???" fish. Finished the story, currently fishing level 23 and caught all of the other fish already. One thing I noticed is that if you go to the encyclopedia and sort by rarity, they aren't rarer then some of the normal fish, the "???" one's are all mixed in, some of them appear to be as low as two stars.
Just looking at the gauge when renting the fishing equipment it looks like level 50 is the max (so level 30 + the level 20 pole?), each level up just says it just allows more tension before the line snaps. Another thought I had is that maybe some equipment like a special bait will be available to buy or win as a prize at some point, or maybe some fish only come out during certain weather conditions or times of day (though I've fished in the rain and at sunset and nothing new so far).
Just looking at the gauge when renting the fishing equipment it looks like level 50 is the max (so level 30 + the level 20 pole?), each level up just says it just allows more tension before the line snaps. Another thought I had is that maybe some equipment like a special bait will be available to buy or win as a prize at some point, or maybe some fish only come out during certain weather conditions or times of day (though I've fished in the rain and at sunset and nothing new so far).