1. Heat a large skillet over medium-high heat. Sprinkle both sides of fish evenly with 1/4 teaspoon salt and pepper. Add canola oil to pan; swirl to coat. Add fish to pan; sauté 4 minutes or until golden. Turn fish over; sauté 2 minutes or until desired degree of doneness.
2. Combine radishes and next 3 ingredients (through serrano) in a medium bowl. Combine remaining 1/4 teaspoon salt, olive oil, juice, and honey in a small bowl, stirring with a whisk. Drizzle dressing over peach mixture; toss gently. Serve relish with fish.