What you are refering to is applied mostly to Red Arowanas. Grade 1 being Super Reds (Chili or Blood Red), Grade 1.5 is Reds. 1.5 Reds are the ones that do not turn Red, they turn pale or pink at the most. Those are "cheap" red ones that are not pure blood, or crossed with another type of aro (greens mostly).
I see that you are from Canada, you can join ArowanaClub.ca if you feel like it. It is a site dedicated to arowana hobbyists from Canada.