If it is the six gallon edge I would not put tetras in it. They like to school and 6 gallons is not very big. You don't seem to be taking this seriously at all either. All of your posts have come off as you being impatient and very uncaring towards the fish you wish to put into your tank. I am sorry if I sound like a broken record but most people here take their fish keeping much more seriously than you seem to, at least from what I see from your other posts.