Very intresting..... I've heard that VZ variants are most aggressive.
My Aimara is also an Amapa variant, and I have had mine with rays well over a year and other fish like a silver Aro, clown knife, Brycon, Barbs, and even Dorado for several months now...... Seems fine with everything I've tried so far. Plenty of room though, the tank is a 750.
Yours came from Shark Aquarium too?