Inshore, the tides play a huge role in where and how grouper will be feeding. Gag grouper and goliath grouper can be found near the mangroves, around bridges and docks. Some of the shallow water hangouts are much more productive during the high tide. Fishing on either side of the high tide will usually lead to some good fishing. The bite slows down during the slack tide.
During the low tide, some of these shallow water spots that are good for grouper will not be as effective. As water levels drop, some areas will not hold enough water along the docks or mangrove-lined shorelines, but some of the deeper water that is found in the nearby channels and holes will still be productive. Some other areas to fish are the deep water docks and bridges. There is plenty of water in these areas to hold good numbers of grouper during the low tide. Fishing while there is some moving water on either side of the low tide will be effective. The slack tide is usually a tough time to catch grouper inshore.
Offshore, the tides don’t play as big of a role on the fishing. Some charter captains report that the tides don’t have any effect on the fishing, while others believe that some moving water is good, but faster currents make it harder to position baits on the underwater structure and chumming becomes more difficult. It is much more important to have some good reefs and wrecks on your gps than to be worried about the tides when fishing the offshore waters. If you can find the reefs and wrecks, there is a good chance that you will catch some grouper.