i think jag catfish only get like 8" (correct me if im wrong) and senegal bichirs usually only reach 8-12" and delhezi's like 14-18" i think and ur tank is 26" wide so i dont think bichirs would be a problem, should go well with eels as well
the boxy lay-out would be nice for some Poly's. I have sens and an ornate with my tire track eel and everyone plays very well. a 90 should be okay for a few Sens full grown. mine slowed down at the 6" mark. what they lack in color they make up for with personality/activeness.