Heat oven to 375 Drizzle oil over the bottom of a 13 x 9 baking dish. Place haddock on top of oil. Sprinkle 1/2 teaspoon old bay seasoning over each haddock serving. Cover with tin foil. Bake for 1 hour or until fish flakes easily with a fork.
Meanwhile, put potatoes in a medium saucepan, cover potatoes with cold water by 2 inches. Generously salt water, bring to a boil over medium-high heat, boil the potatoes until fork tender, about 15 to 25 minutes. Drain potatoes. Place potatoes in a serving bowl, drizzle with melted butter, sprinkle with chives. Right before serving: toss classic coleslaw mix with slaw dressing.