Grate 1½ zucchini with each grater – you want about 1 c of each. Place in strainer in sink and toss with salt. Let drain for 20 minutes.
Meanwhile, put the rice in the bowl and lightly mash. Add onion, parsley, ¼ c arrowroot, lemon juice, seesd, paprika, and pepper and mix well.
Squeeze handfuls of zucchini to get rid of as much liquid as possible, then mix into the rice.
Combine cornmeal with remaining arrowroot in the shallow bowl.
Wet your hands, then take about ½ c of the mixture and form it into a patty. Press it into the cornmeal to coat, then flip and coat the other side. Repeat with remaining mixture.
Heat several T oil over medium heat. When it starts shimmering, add a few patties and fry until golden, about 5 minutes. Flip and fry the other side, then transfer to plate. Repeat with remaining patties, adding more oil as needed.