You won't, however, hear talk of stalking fish in gin-clear water. In fact, except around the outer islands, the water tends to look more like strong tea than gin. Still, potential for excellent sight fishing always remains. Redfish in the 5- to 10-pound range are commonplace almost year round in the shallow ponds and lagoons around the islands and in Back Bay. Gator trout, or ''specks,'' of up to 10 pounds also frequent these waters. But perhaps the biggest attraction for fly-fishermen begins in the fall when huge schools of bull reds, some well over 20, 30 and even 40 pounds, turn up around the barrier islands and eventually push inshore.