Place swordfish pieces into a large glass bowl. Combine the fish, lime juice, and onion. Let marinate in refrigerator for 3-4 hours until fish no longer looks raw in center. Drain and discard lime juice. In a large bowl combine tomatoes, jalapeños, cilantro, green olives, and olive oil. Stir in the fish and season with salt and pepper. Add the orange juice, if too bitter you can add a bit of sugar. Toss well and chill. Just before serving gently stir in avocado.