In a large Dutch oven over medium-high heat, heat 2 tablespoons of oil. Add the onion and cook until soft, about 3 minutes. Add the garlic and red pepper flakes and cook until fragrant. Add the wine and cook until reduced by half. Add the fish stock, drained tomatoes, bay and thyme and season with salt and pepper. Bring to a boil and cook until slightly thickened, stirring occasionally for about 10 minutes
While the broth is cooking, heat 2 tablespoons of oil over high heat in separate large saute pan. Season the bass on both sides with salt and pepper and cook until golden brown on both sides, about 2 minutes per side. Remove to a plate.
To the same pan, add another 2 tablespoons of oil, season the shrimp and saute until lightly golden brown, about 1 minute per side. Remove to the plate with the bass.
Add the clams, mussels, bass and shrimp to the reduced broth and cook until the clams and mussels open, discarding any that do not open, about 3 minutes. Stir in the parsley and tarragon and season with honey, salt and freshly ground black pepper. Add hot sauce, to taste.
For the Sourdough Croutons:
Preheat Grill Pan to medium-high heat.
Stir together butter and anchovy paste in a small bowl. Set aside.
Brush bread with oil on 1 side and season with salt and pepper. Grill, oil side down on preheated grill pan until lightly golden brown, turn over and continue grilling until lightly golden brown on both sides.
Remove bread to a platter and spread some of the butter-anchovy mixture on the seasoned side. Cut each slice in half, crosswise.
Place 1/2 slice of the bread in each bowl, ladle some of the mixture on top and top with the remaining 1/2 slice of bread. Garnish with parsley leaves, if desired.