Lucky you! Curacao is awesome! There are a bunch of good night dive sites there. I've included a link below that you can check out. Keep in mind two things with ostracods....which you may already know....
1. You can't see them everywhere. Only in places with a blue seed shrimp population (that's what ostracods are) like Bonaire. There may not be ostracods in Curacao. I've never heard of an ostracod dive there, but I've also never tried.
2. The best time to see them is 2 to 5 days after a full moon (5th day is optimum). The full moon in May is on May 23rd, so you'd have to make sure you're on island then. If you do see them there, please let us all know. It'd be good info!
Have fun!
Curaçao: The Caribbean Getaway That Sets You Free