no tetras do well with bettas.To fats and will aggetate the betta.You could try a pleco if tank is big enough or oto's cories.Ive heard some one keeping a pk male with cherry barbs with no bothers.
I managed to keep a betta in a community tank with tetras, but at the moment, I have a betta with 3 oto's and he just swims around, looks at them and moves on. They are pretty active too