From what other members have reported, tank size can fluctuate with betta personality. There was a member that got a 5gal tank for theirs, but it was too big for him. He had a more relaxed personality and much preferred the 1gal bowl she moved him too.
But other fish are more exploratory than others and like 5-10gal.
"It is the mark of an educated mind to be able to entertain a thought without accepting it." - Aristotle
"For when Thou art our strength, it is strength indeed, but when our strength is our own it is only weakness." - St. Augustine (Confessions 4.XVI)
Feminist, Neo-Darwinist, Libertarian, Animal-Loving Christian