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 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 skillet or griddle on medium heat and add a bit of oil to coat. 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 golden brown. Work in batches. Fritters fry faster as skillet gets hotter, so watch closely.