Make a roux in a large heavy pot over medium heat: Add oil to pot and heat over medium heat, add flour, it will sizzle when it's at the correct temperature. Use a whisk and stir constantly. Stir until it reaches the color of peanut butter. DO NOT BURN!!
Add onions, celery, bell pepper, garlic, and 1/2 c. green onions. Cook until ingredients are cooked down.
Add water, okra, Rotel, and seasonings and bring to a boil. Reduce heat to low and simmer at least 1 hour. Add seafood and continue to cook on medium for about 15 to 20 minutes.
Taste for seasoning. Add file to thicken.
Stir in remaining green onions and simmer a few more minutes. Serve over rice in bowls.