Add yeast and sugar to tepid water. Leave for 5 minutes. Sift the flour and salt in a pan. Add the above mixture. Stir well, cover and leave for fermentation. Oil the pizza tray.
Spread the well prepared dough and cover with peeled and sliced tomatoes. Grate a small amount of cheese on tomatoes and lay the fish on them. Grate and spread rest of cheese on pizza. Place the tray in 175 for 30 minutes and then serve.