Heat grill to medium-high.
Combine jicama, watermelon, lime and honey, and refrigerate for 30 minutes.
Brush catfish fillets with oil, and sprinkle each with paprika, salt and pepper. Place on grill, and cook for 3 minutes on each side.
Place tortilla on a plate, and add a few arugula leaves; then top with a portion of catfish. Add Jicama and Watermelon Salsa, and garnish with a mint sprig.
Serves 4