I agree, try calling the MNR in the Nipissing region to get an opinion. I'm sure they'd love to hear from you.
Very good thread by the way. We caught some "blue" looking walleye in Northern Alberta a few years ago, I tend to think it was just a pigment thing and not a true blue.
My friend has a picture of a "blue" walleye near Loring, ON in winter. It is on the ice and the snow is stained deep blue from the fish...that fish makes me wonder.
Nipissing also has Blue Perch, we caught them this winter in bunches. They would stain our counters when cleaning them...wonder if that's a related issue at all.