Mangroves provide some excellent cover for many different types of saltwater fish. An incoming tide usually provides the best fishing for redfish near the mangroves. When the rising water gets high enough to cover the roots of the mangroves, redfish will move into the mangroves to feed on a variety of different baits.
An outgoing tide can also be productive, but make sure you get to your favorite fishing spot before the water levels drop too much. Once you see most of the roots out of water, there will be little cover for redfish to hide.