Heat a grill or grill pan over medium-high. Clean and lightly oil hot grill. Pat fish dry with paper towels, lightly brush with oil, and season with salt and pepper. Grill, skin side up, until opaque throughout, about 10 minutes, flipping once.
In a large bowl, combine cucumber, cantaloupe, fish sauce, lime juice, jalapeno, ginger, and mint. Transfer fish to plates and serve with salad.