Cook the spaghetti in salted water according to the package instructions, then drain and fold in a tablespoon of olive oil.
Puree the pine nuts with 100 ml of olive oil, the garlic and the basil leaves in a blender. Mix the parmesan into the pesto and season with salt and pepper. Score the tomatoes crosswise, scald with boiling water, peel and core and finely dice the pulp. Season the fish fillets with salt and pepper and fry them until golden brown on both sides with the remaining olive oil.
Heat the spaghetti, mix well with the pesto, arrange on plates and sprinkle with diced tomatoes. Place a fried fillet on each serving. Garnish with basil.