Yes, you need to buy more fish. Absolutely yes, you need to soak them in distilled or ironized water...
Not included....
The same water you will need to fill up the tank. I used 5 liters.
Soak the fish for at least 3 days.. non negotiable. They will not float otherwise.
This has to be said... But no! Just by putting them in the tank with water won't essentially work.
Our little person actually calms down watching the colours and the fish bubble up and down. This should be a go to for children, possibly young adults who are Neurodivergent/ on the spectrum. Only living with one I know. So no offence.
Down sides: The tank is loud, however our neighbours are loud this seems to help our little person focus on the tank. Think of the kettle on the go, non stop.
2: Make sure to place the tank in a corner it's easy to tip over.
Bottom line though, it's a game changer.