In a large bowl, combine the shrimp and the citrus juice. Cover, and store in the fridge until shrimp are light pink and beginning to firm up, about 1 hour.
Place the red onion in a small bowl with the remaining citrus juice and season with salt. Let sit for at least 10 minutes and up to 1 hour, stirring occasionally.
In another large serving bowl, combine the cucumbers, chiles, red onion (with its juice) and chopped cilantro. Season with salt and stir well.
Remove shrimp from the fridge, and using a slotted spoon, remove from juices to a clean cutting board. Cut into bite-sized pieces, or slice lengthwise, depending on what you prefer.
Add shrimp and its juice to the prepared vegetables, stirring gently to incorporate. Taste, and season with more salt or citrus as needed.