You can keep a fish in a small tank. It's totally okay. Completely fine.
As long as you're willing to do the necessary water changes, which would be like... every other day. And you keep the bowl at the proper temperature.
Maybe I seem like a moron, but I can definitely tell when my fish are comfortable. When I moved Robert into a ten gallon, I thought he would love it... but he didn't. He freaked out, and never calmed down. So I moved him back to his 5gal, and now he's happy.
It depends on the fish what they're comfortable with. But NO fish is comfortable in a 0.5 gallon unheated unfiltered bowl with water changes once a month. They're just not. They'll die.
Robert Falcon Scott - Red salamander HM plakat
Passed on- Friedrich "Freedy"
Four African Dwarf Frogs - Dorkus, Sporkus, Baron(ess), and Bubbles!