Cook haddock according to seafood steamer bag instructions.
Meanwhile, in large bowl, make lemon vinaigrette by whisking oil with lemon juice, shallot, honey and salt. Toss with arugula, quinoa, grapefruit segments and pumpkin seeds.
Divide salad onto 4 serving plates; garnish with blackberries. Serve haddock alongside.
To segment grapefruit, slice off top and bottom of peel to create 2 flat ends. Place a flat side on chopping board. Using a sharp knife, run knife from top to bottom of fruit to slice off peel and white pith in sections. Holding peeled grapefruit over a bowl, cut between membranes to release fruit segments.