What is the difference between the biological stain Alcian blue and Alcian blue 8GX?

And how do I make up a solution to stain fish for identification. What pH and strength would I require? There is so much variation in papers it is rather confusing!

There appears to be no difference. According to this, “Alcian blue 8GX” is the preferred name.

As far as I remember it’s the same stuff.

The most cited work on fish marking with Alcian blue seems to be Kelly, Marking freshwater and marine fish by injected dyes, 1967. He recommends a concentration of 64mg/ml.