No, as stated as above, you can keep multiple female bettas together. But not multiple males. And no male with a female unless you are trying to breed them and are set up for that.
well i have bought a male and a female and soon to be getting a few more females
male is a lovely medium blue with a bluey silver tail fin
and the female is a lovely ruby red
ummm be advised that betta breeders introduce males and females only long enough to make babies, and even then the females often get it so bad that they die....
I wouldn't advise keeping multiple betas in the same tank.
fishman did your crays really eat your beta? sounds like a bit of a whopper to me....