Galvanizing is done with zinc, which can be harmful to your fish, and if you eat your fish, who's going to get those toxins?

The only way I would use Galvanized tanks is if I had the bucks to paint the insides with food-grade paint, which is very expensive. I'd rather take my chances with plastics. Personally, I'm planning on lining plywood tanks with glass, using silicone calk.
I've got one wooden tank (still not done with it) that's lined with pond liner, that's the way I'm going until I can get enuff salvaged glass to start my "glass tank" project!