Wash & dry the fish fillets, season with salt & pepper then sprinkle with the juice of 1 lemon, set aside. Mix the flour, bread crumbs, & paprika together in a bowl.
Peel the zucchini & slice into 1/4 inch thick rounds. Heat the olive oil in a frying pan. Coat the zucchini with the flour mixture then fry on both sides until brown. Place on a plate covered with paper towels to remove excess oil.
In the same oil cook the onion until soft. Add the tomato sauce, harissa, garlic, salt & pepper. Cook, uncovered, over medium heat for 10 minutes, stirring frequently. Add the juice of the remaining lemon to the tomato sauce.
While that is cooking heat 1/2 inch of canola oil in a skillet. Dip the fish fillets in the flour mixture, beaten egg, & in flour mixture again. Fry in the hot oil until the fish is done, should be flaky. Drain on paper towels.
Place the fish & zucchini in a shallow serving dish & top with the sauce.