Combine fish, lime juice, and oregano in large glass bowl. Sprinkle with salt. Chill until fish turns opaque, stirring occasionally, about 50 minutes.
Strain almost all lime juice from fish; return fish to bowl. Stir in onion, minced and sliced jalapeños, coconut, and cilantro. Season with salt. Chill at least 20 minutes and up to 2 hours. Serve in Martini glasses. Pass crackers separately.