BLUE SPOTTED RAY WATER CHANGES ?

I was wondering IF the Blue Spotted Pacific Sting Ray  needs the 40 % of the
water replacement TWO times a Week like the freshwater rays from South
America and the Freshwater ray from Florida  Yes Florida DOES have a
freshwater ray like it's Atlantic counterpart only it lives in freshwater
and does need the massive water changes..  I am running on the assumption
that the drastic water changes are a must for salt water rays.  Thanks in
advance.

Robert G Smith