I was thinking about naming him Mitsu (meet-su, like, Mitsubishi), meaning three, because he is my third betta fish in my entire lifetime, but I haven't made a final decision just in case I happen to find another name I like better. Mitsubishi means three diamonds, so I could name him that and call him Mitsu for short. Not sure how I feel about naming my fish after a car, haha, although I'm really going for the underlying meaning.
Someone also suggested the name Bahari (I think) in some language I can't remember that started with an S haha. It means Ocean. I like it, too.
I want an elegant, unique yet somewhat simple name that has meaning :p but of course I usually have strange tastes in names and whats elegant, unique and simple to me probably won't be to someone else.