My uncle and dad are the people who told me about the 1 gallon per inch of fish rule, so when I brought my son's Betta home in a 1/2 gallon, they both shook their heads and gently reminded me that a small tank is not healthy for a fish. I reassured them I would be getting a bigger tank in the near future, and I did. She's in a 5 gallon, filtered and heated tank, and I have a male in a 3 gallon tank. My mom..., she doesn't really say much about my hobby. My hubby, who knows very little about fish, firmly believes that 5 gallons is the absolute minimum a Betta should be in and has been gently telling me that the male needs a 5 gallon tank too. My hubby also has a thing about symmetry, so he feels that the tank area is unbalanced, but he also feels that the male will be happier in a 5 gallon tank. I will be getting one soon, especially now that the male's sbd is better (I didn't want him in anything bigger until he was better because I didn't want him to struggle too much to swim to places).