[Betta Nerd]

2.5 gallons are the minimum for any betta plus he's probably much happier in there than in a dirty vase he's a handsome glow betta I can't believe how big bettas grow and change over time

 

[Betta Nerd]

Hello and welcome to the forum!
He's a gorgeous boy, does he have a name?

I've always been a fan of the rectangle 5gals. They can be easily found at PetSmart.
For durability, I've got two TopFin 5gals that have lasted me several years with no issues. Just sharing, if you're concerned about how long they last.

Beyond that, size is up to you. If you want bigger, go for it!
I'm also going to disagree with Betta Nerd for a moment. There's a lot of different opinions on what size Bettas should be in minimum, with the common mentality being 2.5gals. As there's no scientific proof backing up what size is best for Bettas, 2.5gal minimum is still expressed as an opinion.

Though, if anyone happens to have unbiased, scientific proof on Bettas needing a certain tank size, I'd be fascinated to hear it! And please correct me too.

Anyways. Size is totally up to what you can fit, afford, and prefer! And welcome again!

Actually I'm not using a bias opinion I've done much research and the minimum size for a male is 2.5 and female is 3.0 now you can choose whatever size you want but my girl is happy with a 3 gal though it looks a bit bigger as of what Eridanus said about the tanks I've had the same tank I bought from there running for 9 years

 

[Betta Nerd]

Yes actually bettas can recognize water movements and if you day their names enough they can recognize their names