im playing the DOS version, and if u beat the Captain's in fynn, they are rank 5, which brings up your stats by a lot, but they have 750 hp and high defense, but you can take them down with magic, they give u the flame bow which is very strong and can be sold for 2000 gil, the golden armour which can be sold for 1000 gil, the curse tome which i havent gotten yet, or the toad tome which can be sold for 5000 gil, they also give 300 - 450 gil for beating them...