Im sure im missing a few but there are upper jaws that stay on the smaller side except for ornates, weeksii, and teugs and lower jaws that grow larger.
Google some of these and see what you like and what would be available to you. I read some where that spencer jack (in canada) had polypterus in the past maybe try there and like dmd suggested wetspottropicals.
Upper jaws
Delhezi
Ornates (get big)
Weeksii (get big)
Teugs (get big)
Palmas polli
Palmas palmas
Senagal
Retropinnis
Mokelembembe
Gold dust
Lower jaws
Congicus
Endlicheri
Lapradei
Pbb (polypterus bichir bichir)
Ansorgii
And enough variants/catch locations that will make your head spin lol
Im sure missed some the other mre experienced members will chime in. I learn something new about these fish every time i log in to the forum
sooo happy with them, and they get along with all my other fish and each other they all have their own spots in the tank pretty much sometimes I even catch them sharing spots and swimming together lol appreciate all the help and info for sure this forum is great 
