Wash and dry the fish. Rub all over with salt and turmeric powder. Set aside.
To make the batter, mix all the batter ingredients. Add water at the end. You want a little thick, but smooth batter. Set aside for 10 minutes.
Heat the oil in a deep frying pan. Dip each fillet in batter and swirl to coat. Deep fry in batches till golden brown. Make sure oil is not overheated otherwise the fish will not cook inside. Take fish out of oil and drain excess oil on some paper. To serve, lay out all the fish on a large serving dish. Sprinkle with chat masala and arrange lemon wedges on the side. Best served immediately.