For flounder in Florida, a white grub is okay. I would use a scent on my grub tail like Pro-Cure. You can also tip it with a piece of shrimp. It will make a much more effective technique for flounder. I prefer using some live baits for flounder like a Creek Chub (also called bull minnow or killifish), finger mullet or live shrimp.
Flounders can sure be caught on the right lures.
I would use them on a 1/8th or 1/4 oz. jig-head and drag them along the bottom. The other way is using a fish finder rig with a shorter leader, to keep the bait closer to the bottom near the flounder. When beach fishing with a fish finder rig, many anglers use a pyramid sinker.
But for flounder fishing I prefer an egg sinker, so the sinker can roll down-tide with the current and cover more area. The pyramid sinker will set itself in the sand and stay in that one specific area.
The most important thing to remember when flounder fishing is they are a light-biting fish. So you have to be a line watcher. I use the Hi-Vis lines when flounder fishing so I can detect when the line jumps, moves or changes its direction. When the tide is running one way and your line starts moving in the opposite direction good chance it is a flounder that grabbed your bait. This is common to flounder beach fishing.
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Captain David M. Rieumont
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