I know you're stock isn't the main guys for jumping. However having worked with marine rays for a substantial period of time I have found that in captivity they can often circle their enclosures at the waters surface, and when spooked even by another fish they can sometimes come out. These rays were in a tank 35foot across, 4 foot high and 20 feet bredth, so they weren't short of space. I would hate to see you lose some of that awesome stock.