Depends on the time of year. This end of the season I will not use anything UNDER a 1/0 and will use a 4/0 frequently with baitfish/deceiver types 6" - 8" long. You can still cast these 30 yards on a good #8,, provided they are tied well.
Early season, I use smaller hooks and smaller dressings, buteven then a size 1 is the very smallest I use on bass.Even 10" bass will wolf down a 2/0 and a 3" - 4" fly. Sparse clousers will be tied on a size 1, then hooks to suit the tying.
At this time of year, sandeels are well grown, so even a sandeel pattern (and you only need ONE, the DNA clouser like this one pictured) tied sparse is "6 long and on a 1/0 hook with 5/16 eyes.
For this type of tying a larger hook, because the flyis MUCH larger. This one was 6" long too.
A school bass of 1.5lb will take a whole mackerel, so why use tiny morsels unless they are locked on to herring fry or brit?