if i remember right the tank the rays were in were you brought them was a bare bottom tank if this is true the rays are just enjoying the new gravel
when you set the new tank up try to use a much smaller type gravel
cane will know what they were feeding on feed the same until they are settled
everyone panics with new rays as they hear how hard they are to keep
but you have added a few fish lately so test all the water parameters and let us know what they are
amonia has to be 0 or the rays will die fast the same with nitrie
rays can handle a wide range ph from 5.5 to 8.5 but it has to be kept stable with no big changes
nitrate well just keep that as low as possable mine is always 80-100 and the rays bred in that
temp i always keep mine at 84-86
if unsure do a 25% water change rays love new water