Assuming glass.
I looked at glass repairs, some time ago. Light scratches can be removed with specialist fine polishing compounds and high speed polishing disk. And lots of care….
I do not think the compounds are going to be good for your fish. Then you have the problem of carrying out the actual polishing high-speed drill and water do not mix.
If the scratches are deep ie. Your fingernail stops in the scratch – you may need to use a glass resin – (like glue) the problem here is two fold. 1. You will need a UV light to set the glue, 2nd you will need to polish!
To top all of that – there is still no guarantee of complete success.
I would suggested leaving it and keep it clean of green alge. Or replace the whole plain of glass..
Sorry
Jason
