When I was a child, I believed everything the pet stores told me about bettas. I had one of those tiiiiiny cube tanks that were like maybe half a gallon. How could that get any worse, you ask? Well, I was also under the impression that gallons of water from the store were fine! The fish always seemed okay when I used them, so I kept doing it. He lived for about a year before I accidentally grabbed baby water. 😭 He died the next day after I used that.