Grate 1 tsp. of lime zest and squeeze 5 Tbsp. juice from limes.
Combine 2 Tbsp. of the juice with 1 Tbsp. oil, chili powder, and ⅛ tsp. pepper in a small bowl. Place the fish in a sealed plastic bag and set in a shallow dish. Pour in the lime mixture, seal and turn to coat the fish. Marinate in the refrigerator for 15 to 30 minutes.
Meanwhile, combine raspberries, pineapple, green onion, jalapeno, 1 tsp lime zest, 1 Tbsp. lime juice and the remaining 1 Tbsp. of oil, and ⅛ tsp. pepper in a medium bowl.
Combine yogurt and the remaining 2 Tbsp. lime juice in a small bowl.
Coat a 12-inch nonstick skillet with cooking spray and heat over medium-high heat. Add the fish (discard marinade) and cook, turning once, until it flakes easily, 4 to 6 minutes.
Break the fish into bite-size pieces with a fork. Serve in tortillas topped with lettuce, the salsa, the yogurt mixture and cilantro, with lime wedges on the side, If desired.