To set a successful trotline, first, you have to know where catfish live or travel in the water body. Find them by fishing with a rod and reel, or know that others have caught fish in the area.

Go over the area with a fish finder, noting depth and substructure. Get to know the area and the locations of it's features, such as drop-offs, brushpiles, submerged logs, stumps, etc. The last step in selecting a place for setting a new trotline is to drag an anchor over the bottom to discover if there are other lines set in the area. If you set your line over another line, when the fisherman runs that lower line, he will raise yours and possibly run both lines. Worst case, your line will be cut and your hard work will be wasted.

In the warmer months, most fishermen set trotlines in deep water, much deeper than needs be. Most larger catfish will roam in the shallow water actively feeding at night. I like to set my trotlines in three to five feet of water near to and parallell to the bank, baiting the hooks only at night.