would a Green Arowanna be ok with 2 channa bleheri, they are all roughly the same size now however the Arow will out grow them within the next 6 months?
As you said, the green aro will outgrow the bleheri fairly fast. Bleheris wouldn't make suitable tankmates anyways, they only reach ~6" max size, a little small for a large powerful fish such as an arowana