I have three bettas, and here's a quixk summary of how they all got their names c:
Rodge - I was very obsessed with a Youtuber Brandon Rodgers at the time, and I wanted to name him off of him somehow. I don't really like the name Brandon, or Rodger, so Rodge ended up being his name c: (think this was about the time #notmyrodrick was happening too, might've been a factor lol)
Tarou - The name means 'big' from what I am aware of, I knew I was getting a twin tail halfmoon and his tail would be huge, so there we go!
Jupiter - I knew I wanted to name him something mythological or planet-related. He was going to be Venus, but when my friend offered the name Jupiter, I knew it was meant to be!