Glue Residue Inside A Fish Tank

I bought a 20 litre tank at Pets at Home, which I planned to use as a QT/fry/general purpose tank. Maybe convert it into a shrimp tank in the future.

When I got it I didn't notice the piece of cardboard with the brand name etc was glued to the inside on the tank glass. I got the cardboard out, but a stripe of glue and remains of cardboard are still there. Tried to scrape it off (wasn't doing that very vigorously to not scratch the glass/acrylic), let it soak for a few days, etc, but nothing's worked so far.

Any ideas how I can get rid of it? If I leave it in, is it possible it will harm the fish?

Thank you for your reply. I didn't expect anyone to give me a definitive answer with so little information. I guess I'm just fishing for ideas and asking on the off chance someone has had a similar experience with a tank like this.

I don't know what kind of glue was used. It doesn't seem to be silicon though. I've sent a message to Pets at Home, I'll see what they say.

I'm reluctant to use a DIY solvent on the inside. It might create more problems than it solves. Scraping doesn't seem to work, I'd have to use a razor blade or something to get it off. Really nasty stuff.

Thank you, that's a great idea. I'll give it a go.

Thanks for your input. I'll try a scourer tomorrow.