Actually, I am not totally adverse to all this 'grading' bollocks. Clean three bar are sold off first, then clean four bar. Dirty three bars get left over and sold cheap, and are my favourite.
Another term, 'high quality', dunno what that means at all.
There seems to be an industry of buying a batch of IT fry directly from Sumatra, growing them out minimally, and splitting them into sub-batches, passing them on, and inventing grade and quality.
Don't think the fish care at all.
Be careful how you spend your money.