I can't wait for the 1.5 update to come to android I've completed all the quest and I'm running out of things to do
Crab pots are an easy way to get guaranteed fishing XP every day.
This. Crab pots are by far the easiest way to get fishing XP tbh. However, if you don't want to go that route, fishing in the river in town and the "lake" outside of the mines will work too as the fish there aren't incredibly difficult to catch and will typically net you some good xp. Upgrade your rod as soon as you can and don't be afraid to use some tackle and bait.