you might wanna float them in a betta cup or breeder box for a while, and pay close attention to how he reacts. a breeder box might be best so you can see how he reacts not only visually but to their smell as well (sometimes a betta will be fine when he just SEES a tankmate, but his predatory instinct kicks in when he can smell them too)
So remember, when you're feeling very small and insecure,
How amazingly unlikely is your birth,
And pray that there's intelligent life somewhere up in space,
'Cause there's bugger-all down here on Earth.
Loki/Grendel/Gail/Beowulf/Camilla/River/Bathory/Arwen/Lafayette/Deb/Jack Skellington (soon)