Sauté the vegetables over low heat for 7 or 8 minutes or until the onions are soft and translucent and the bell peppers are tender. Stir in 1/3 cup of roux, mixing well. Stir in the undrained canned tomatoes, bay leaves, salt and pepper. If the sauce is still a little thin, stir in a couple tablespoons more roux, mixing well.
Return the browned chicken to the pot. Strain the Fish Broth and pour 5 cups broth into the gumbo pot, stirring until well-blended. Increase heat a bit until the gumbo sauce is bubbling, then reduce heat and add more broth if needed.
Cook the gumbo uncovered, stirring occasionally, for 50 minutes to 1 hour or until the liquid thickens to the consistency of heavy maple syrup and the chicken juice runs clear when cut to the bone.
If using fresh okra, rinse the pods, cut off the woody tips and discard. Stir okra into the pot (whether fresh or frozen). Cook gumbo about 20 minutes longer or until okra is almost tender. Add shrimp and cook, stirring gently from time to time, over low heat for about 10 minutes, or just until shrimp are pink and tender.
Taste gumbo and add more salt, black pepper or hot pepper flakes, if desired. If you prefer a thinner gumbo, heat remaining stock and stir into pot, then stir in the gumbo filé, if using. Serve gumbo in warm shallow bowls over rice.
Variation: Duck legs and thighs can substitute for the chicken in this dish, adding a real heady note to this old Southern classic. Buy small size duck legs and thighs and trim off all excess fat and overhanging skin. Rub the bottom of a large heavy skillet with a wad of the excess fat and then set aside the fat. Proceed with the recipe as with the chicken.