A fishfinder is not just for staring at, it is a tool for building a plan. Modern units show you the bottom, the structure, the bait and the fish, and they mark and revisit spots with GPS precision. Learning to read yours is one of the fastest ways to catch more fish, whether you are hunting sea bass over a wreck or tuna over the bank.
The three views
- Traditional (2D) sonar: shows what is directly under the boat, the bottom hardness, bait balls and fish arches. Best for marking fish and reading the water column.
- Down imaging (DI): a photo-like view straight down, superb for seeing structure, wrecks and individual fish clearly.
- Side imaging (SI): scans out to the sides, so you can find structure and fish off to the boat before you are on top of them, a game-changer for covering water.
From screen to fish
Use the sounder to find the structure and the bait, then fish it deliberately. Mark productive spots and depth changes as waypoints so you can return. When you mark fish stacked at a certain depth, put your lure or bait at that exact depth, that is the whole point of having the technology.
Tip Learn what your bait marks look like, and fish under them. Gamefish hold near the bait, so when you find a bait ball or a school on the sounder, that is where to drop, the fish are rarely far from their food.