How do I attach bait to my fishing rod in Stardew Valley's Android version? I tried various forms of long pressing and it hasn't worked yet.
Drag the bait over the fishing rod to attach the bait. This requires a better fishing pole than the one you start with, so either the Fiberglass or Iridium one.
There is no easy way to remove bait again on the mobile version of the game, so don't attach all your bait to the second-best fishing rod, which you can't easily get back when you upgrade to the Iridium rod.