Clean the fish, cut it into large pieces and season with salt. Pour the tomato juice over the fish and let it sit for about half an hour. Dice the onions. Place onions and fish heads into a large pot, cover with water and cook over high heat. After about 30 minutes, add remaining fish and cover the contents with water.

Cook for about 20 minutes more before adding sweet paprika, hot paprika and 2-3 tablespoons of salt (or to taste).
Cook for another 15 minutes and serve.