Use a large pot or high wall frying pan and pour in it the oil. Place on high heat and insert a thermometer aiming for 190°C. If you don't have a thermometer, you can test the oil temperature by adding a small piece of bread to the oil. If the bread browns in about 30”, the oil is ready.
Use a flat dish to add the flour along with the salt, pepper and the coriander. Mix well and dredge in them a handful of the Atherina. Then place them in a fine sieve, shake couple of times to remove the excess flour, and dip in the hot oil. Don't overcrowd the pan. If you add too much fish to the pan at once, the temperature of the oil will drop and the fish will not cook evenly.
Immediately we use a slotted spoon to give them a good stir in order not to stick between them.
Cook for couple of minutes and drain the fish on parchment paper. This will help to absorb any excess oil, leaving you with a light and crispy fish.
Repeat the same process for the rest of the Atherina and serve immediately. This dish is best served immediately, while the fish is still hot and crispy.