A list of things to make sure of when trying to fish with a rod in the unreal world.

* Using a rod? (hook type doesn't matter noticeably)

* Have a reasonable skill level? (Preferably 60+; 50+ can still net you okish success rates)

* Not too encumbered / wounded / starving / or fatigued? (these all reduce success rates)

* Uncooked meat bait? (Some other bait types can get you fish, but less often and in smaller quantities; using turnips, bread, or cooked but unspoiled meat for example)

* Fishing in deep water? (Rivers and multi-tile lakes seem to work best IMX)

* Cycling fishing locations? (Areas can be overfished; also fishing too many times in the same place can upset the water spirits)

* Not getting nightmares or other bad signs from the spirits? Though you should be aware that forest spirits aren't water spirits. Water spirits are only placated with fish sacrifices IIRC.