How do you fish?

I have a pro fishing rod and made some fish bait from bread, but wherever I go and try to use the rod, it tells me there’s no fish. Not in swamps, nor in the rivers. What am I doing wrong?

The river has no fish mobs nearby, you may see some fish stuff.

Yep, fishing actually requires that fish be around to catch. They tend to pop into the shallows every so often if any are around.

(Fishing spots can be fairly infrequent, though: you shouldn’t expect to find fish, generally. More along the lines of “mark where you see 'em, when you see 'em”.

There was an issue with zeds depopulating rivers of fish several revisions ago. If you save is old, the rivers may actually be empty.