Cut carrot, leek, and zucchini pieces lengthwise into julienne strips; set aside.
Bring Lobster Stock to a simmer in a medium saucepan (do not boil); keep warm over low heat.
Heat oil in a large skillet over medium-high heat. Sprinkle fish with 1/4 teaspoon salt and 1/8 teaspoon black pepper. Add fish to pan; cook 2 minutes on each side. Remove from pan; keep warm. Melt butter in pan over medium-high heat. Add mushrooms and leeks; sauté 2 minutes. Add carrot; sauté 2 minutes. Add zucchini, Lobster Stock, 1/4 teaspoon salt, and 1/8 teaspoon pepper. Arrange fish over vegetables; cover and cook 3 minutes or until fish flakes easily when tested with a fork.
Place 1/2 cup vegetables into each of 6 bowls; top each serving with 1 fillet. Ladle 1/2 cup broth over each serving.