Tips for minimizing smells? Trying to sell fiancé on an aquarium!

So- long story short is my fiancé had siblings who owned several different pets growing up. He very much did not like the smell involved for some of them (namely aquatic animals and guinea pigs).

Recently we hit up a pet shop just to look around and I brought the possibility of getting something a bit smaller, like shrimp. The tanks there did have a bit of scent to them but it was more 'aquarium' and less animal waste, if that makes any sense. Still too much for his liking.

I was wondering if there was any way to mitigate any possible smells besides regular maintenance and cleaning? The list of animals we can have with our current lifestyle is very short so I was wondering if there was some possible solution I could talk to him about.

The likelihood of us getting any kind of aquarium is still pretty low but solutions would be good to keep in mind! Thank you so much!