In a large stockpot, bring water to boil. Whisk in Kary's Roux and whisk occasionally until dissolved; about 5 minutes.
Remove rib meat off chicken and discard. Finely chop chicken breasts ( little pieces) then add to pot.
Finely chop green bell pepper, onion, garlic, and celery. Alternatively, it may be finely chopped in a food processor. Add to pot.
Whisk in cajun seasoning, salt, black pepper, and celery salt.
Cook over medium-high heat for about 40 minutes lid off, stirring occasionally. Cook additional 10 minutes with lid on. Gumbo is done when chicken is cooked.
Serve with cooked rice. Top each bowl with finely chopped green onions and parsley or add to pot.