Take the mullets, rinse them under running water and using scissors remove the part of the belly with the entrails. Rinse them again and keep them aside. Repeat the same operation for the cod, but for the anchovies and cepolas you just need to rinse them. Now move on to the calamari. Remove the cape from the head and remove the internal cartilage feather. Wash the coat under running water, cleaning it of entrails. Make a slight incision and pull the skin away using a small knife. Wash the squid again under water, then cut the fins to separate them from the mantle and cut the rest into rings. Take the part of the tentacles and using a knife remove the part of the eyes; then by pushing out with your fingers you also remove the beak contained in the center of the tentacles.
Also rinse the prawns under water. When all the fish are clean you can move on to frying. Heat plenty of oil in a pan, it must reach a temperature of 180-190°; measure it with a kitchen thermometer. In the meantime, pour the semolina into a low, wide container. When the oil has reached temperature, flour the cods completely.
Remove the excess semolina and immerse them one at a time in the boiling oil. Also flour the mullets and fry these too together with the cod. Wait 3-4 minutes and when they are golden brown, drain them and transfer them to a tray lined with straw paper. Then also flour the squid and use a sieve to remove the excess flour by shaking it. Fry these too for a few minutes until they are golden and transfer them next to the other fish.
Then flour the anchovies and remove the excess semolina as just done. Immerse these in the oil too. Then also flour the cepole and fry them together with the anchovies. Wait a couple of minutes and when they are golden brown, drain these too and transfer them to the tray with the straw paper.
Now take care of the prawns. Pass them in the semolina and immerse them in the hot oil. Wait about 1 minute and when they are golden, drain these too, transfer them to the tray together with the other fish. Decorate with lemon wedges and serve the mixed fried seafood while still hot. Enjoy your meal!