The core game mechanics are creative with the time you had to develop. I would have loved to see more difficulty building up when fishing. Maybe fishes resisting or breaking away from the hook. The fishing line could have some slight physics as you move the boat instead of straight up and down direction. I think after 3-4 days, the repetition really starts to show and the urge to continue playing dwindles more so.
Speaking of days, each day is "Day 1" which doesn't help me as to how long the progression goes, I noticed the fisherman getting older which was pretty cool. The use of a narrative is good between days but it would be nice to hear some more narrative as I fish. Maybe the narrative can be a slight tutorial and explain what the player should be doing in a more creative way.