Place shredded zucchini in a linen towel and squeeze really well, twisting at the top and pressing on the “ball” with zucchini. I have squeezed about 1/2 cup of water.
Discard liquid and transfer zucchini to a large mixing bowl along with tuna, eggs, Parmesan cheese, mayo and salt. Mix really well, breaking tuna into pieces. Sprinkle flour on top and mix until well combined.
Preheat large ceramic non-stick skillet or griddle on medium heat and spray with cooking spray or add a bit of oil and spread with spatula (my preference). Add about 1/3 cup mixture (don’t flatten too thin), fry for 4-5 minutes, carefully flip and cook another 4 minutes or until brown. Work in batches. Fritters fry faster as skillet gets hotter, so watch closely.
Serve hot or cold, with a simple Greek yogurt/kefir + garlic + black pepper sauce if you wish (optional but so good).