Pam's Poached Fish Soup

Melt butter in a 5- to 6-quart pot over medium heat. Add onion, celery, and carrot; saute until tender, about 5 minutes. Pour in chicken broth, tomatoes, wine, and lemon juice. Bring to a boil. Add tilapia, herbs, salt, and pepper. Reduce heat, cover pot partially, and simmer until tilapia starts to flake, about 10 minutes. Transfer tilapia to a plate and cover to keep warm. Simmer cooking liquid until slightly thickened, 10 to 15 minutes. Return tilapia to the pot and heat through, 1 to 2 minutes.