also you can get any Palmas Bichir ,or Moke Retropinnis just the lower jaws stay away from Ornat and Tesuguli an Weeksii they do get a nice sizes to. and you can get a Rope Fish.
You didn't even know the difference between the two. Raise both yourself before you go spitting info on the forums. A delhezi would be just fine in a 75gallon. What is it 18'' wide...? what is the problem?
Go with a delhezi if you can find them. I have 3 and they are among my coolest (most personable and most beautiful) bichirs. My weeksii is also pretty cool.