Combine the tomatoes, corn, green beans, basil, vinegar, 3 tablespoons of the oil, ½ teaspoon salt, and ¼ teaspoon pepper in a medium bowl.
Heat the remaining tablespoon of oil in a large nonstick skillet over medium-high heat. Season the halibut with the seafood seasoning. Cook until opaque throughout, 3 to 5 minutes per side.
Serve the halibut with the succotash and corn bread.