The fishing is pretty funny, I can understand why we won't get paid for every fish, since the "target" fishes yield so much.
Picking the right lures is a bit trial and error. The list posted here earlier doesn't seem to be the exact "you need this or you won't catch any". I think there's more to it, but the mechanic is a bit unclear. Some subtle hints would be very welcome. Not sure what all is involved. Color (or, fish X can't see color Y), size, shape/lure movement. So, hints would be welcome.
Some things I'd REALLY like to see:
-More fishing locations, like the river and Naomi's beach, maybe also hire a boat.
-Option to buy lures in batches of 5, instead of only 1 of each type. Any fisherman knows he will loose a lure or two eventually, so bringing a spare or two wouldn't be that weird. It saves some annoying back and forth going (or save scumming) when aiming for a specific fish. This would be a convenience fix, without altering any other mechanics.
-Find random stuff, like boots, pieces of rope, maybe a very rare seeweed dress (fits all girls, but you can give it to only 1, so you'd have to catch another, if that even exists if you want to dress up more girls in it)