That's a small tank for sure, do you know what it was originally marketed to house?
If it were me I would only use it for something tiny, like those kiddy things they sold for "sea monkies". Maybe a snail.
I was in a similar position with my niece a short time ago. She loves my tanks and wanted one of her own, to which my sister agreed. They came home with something not all that much bigger than your own.
Me, being the clumsy and terrible uncle that I am "accidentally" dropped the tank, cracking it and making it unusable.
I then bought her a 64 litre as an apology.
Does Nanna Lou have similarly buttery fingers?