The phrase "fish or cut bait" is an idiomatic expression that means to make a decision between two options: either take action and do something productive, or abandon a course of action and move on to something else. It's often used to encourage someone to make a choice or take action when they're stuck in a state of indecision.
The origin of the phrase is rooted in fishing. When fishermen go out to catch fish, they need to either "fish" by actively casting their lines and trying to catch fish, or "cut bait" by cutting up bait to use as fishing bait for the lines. In other words, they need to either actively participate in the fishing process or assist in the effort by preparing bait for others to use.
Metaphorically, "fish or cut bait" means to either actively engage in a task or project, or to step aside and allow someone else to take over. It's often used in situations where time is of the essence, and a decision needs to be made quickly in order to move forward.
Overall, the phrase "fish or cut bait" is a straightforward way to encourage someone to make a choice and take action, rather than continuing to waver and delay.