Just because you can't see the ban hammer, doesn't mean she isn't holding it
To the OP, a 1 gallon probably wont fit a 6" fish, especially polypterids who haaaate confined spaces, it makes them freak out and jump either until they hurt themselves, or they bust out of the tank and die on the floor.
Please, save your self a headache and the bichirs it's life, get a bigger tank first.
The fish aren't going anywhere, they've been around millions of years
I think your eyeballing measurements are a little off. If it was a "little" birchir, I'm sure it wasn't six inches. Because I would definitely not consider my poly "little" and he's almost 5 inches. He is still a baby, but you know what I mean
Also, I wonder if your tank is really 1 gallon? I bet it's atleast a five