Tap to cast rod. If rod goes down, tap to start fishing minigame. Keep the green bar under the fish to make the progress bar go higher. Hold to make the green bar go up. Let go to make it go down.
Stardew Valley Fishing inspired. Not exactly the same, of course. Tried to recreate the bream in Stardew for the fish. Took the progress bar from Griffpatch's health bar which I then modified to go vertical.