Wash the gobies and remove their fins. If desired, remove the heads and insides as well. Soak them in water with vinegar or lemon for 1 hour.
Chop the onion and boil it in 8 cups water. When softened, remove it from the broth for a time. Put the gobies in its place.
Boil them for 10-15 min., then take them out and chop them. If desired, remove the skin of the fish also. Put the rest of the meat back in the soup.
Add all of the spices, butter, tomatoes and the onion. Boil the dish for another 10-15 min. on low heat and then remove it.