Hystrix, like most other rays, should live a long time (10+ years). I've had mine for almost 4 years now. Larger rays will eat quite a bit. I feed mine every day, and often skip one feeding a week. Usually enough to round their bellys a bit. I'm not a proponent of stuffing them full everyday.
If you order some hystrix from your vendor, make sure they are from Brazil. There are other rays labeled as "hystrix" but they aren't. It will be a good idea to quarantine them too.
If you order some hystrix from your vendor, make sure they are from Brazil. There are other rays labeled as "hystrix" but they aren't. It will be a good idea to quarantine them too.