55 Gallon Oddball Tank

bichirs will grow too big for the standard 55 imo. I wouldn't put them in anything less than a 6ft tank to be honest.
 
I've looked into Knifes, but I think they grow a little large for a tank only 12" wide? What do you guys think of my proposed set up?
 
I would be careful with an african butterfly fish, simply because they are susceptible to nippy fish and you will need a tight fitting lid as they can be jumpers.
 
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