Place fish and lemon juice in a bowl. Season with salt. Set aside for 10 minutes.
Place ginger, garlic, ground cumin, ground turmeric, ground coriander, ground black pepper, red chili powder and yogurt in the bowl of a food processor. Season with salt. Process to a smooth paste. Add a little water if required.
Add this mixture to fish. Mix well until the fish pieces are evenly coated. Marinate for 15 minutes in the refrigerator.
Thread fish pieces onto the skewers. Leave a one-inch gap on the top of the skewers. Grill the skewers for 5-7 minutes, flipping halfway through.