Unfortunately not easily from glass. I've never tried it personally, but know a few whom have and reported varying results from "worked perfect!" to "screw it I'm buying a new tank". The tanks have to be empty and should use something like this. A quick google search will warrant more results as well.
If u can feel the scratches with using your nails..... No. But otherwise you can use this glass buffing powder. I can't remember what's it called. But I'm sure if u google it you can find out what it is.