I tried a fish tank with the kids a few years ago. And puted aldrovanda in it.
It is really cool in the beggining but quickly become a lot of maintenance.
When the seaweed settles, it is necessary to clean the glass and the pebbles once a week and to change a part of the water periodically too ...
If you're ready for that, you can check on kijiji for used fish tank. In my area there's always some 10 gallons available. Sometime fully equiped for cheap.
If it is for growing utric or aldrovanda ... I would recommand sticking to pots.
I was thinking like cutting it back when it gets out of hand. I thought I saw a photo somehwere on the net with a utric growing in a wineglass. I should probably just do that instead and just get a tiny fish tank.
I keep a tank with U minor, U macrorhiza, U gibba and now U graminifolia that I just got from Willy. My aquarium is more of a pond I have always been fascinated by ponds ever since I was a kid catching tadpoles water stick bugs and toe biters.
In this aquarium I have other plants, guppies, loaches to keep out the snails and bristlenose pleco’s to clean the glass so I never have to. I don’t use a bubbler or any aeration other than the non carnivourous plants themselves. Most bladderworts don’t put oxygen back into the water like other plants in fact they use it up. So finding a balance is important. I’m sure size matters a larger aquarium will find a balance easier the smaller the more it will fluctuate. Give them lots of lighting I have two four foot fixtures on for 12 hours a day. All I do is a 1/4 water change once a week, feed the fish and take out handfuls of plants when they grow too much.
The U minor and U gibba are easy to grow and float on top of the water
U macrorhiza Is more finicky it also gets big growing up from the bottom and across the top.
U graminifolia is new to me but I hope to grow it along the bottom like grass similar to this picture.