Cut the fish into small, uniform cubes. Place in a glass bowl and cover with lime juice. Marinate for 30 minutes in the refrigerator - the fish will "cook" in the acid.
Dice the cantaloupe, cucumber, and red onion into similar-sized pieces as the fish.
After 30 minutes, add the cantaloupe, cucumber, onion, and minced jalapeño to the fish.
Drizzle with olive oil.
Add the chopped cilantro and season generously with salt and pepper.
