Not saying you shouldn't get one...just be very careful what you put in with it. I've pretty much built my setup around the bichir, because I love them that much. I know he will leave my middle/top swimming gourami alone, the knife fish could not care less and even "snuggle" with him in a rock cave sometimes (your experience may vary...a LOT), he won't even bite the pictus cat's whiskers when he is right next to pictus cat, and really all he does is try to sneak up on a cory but never really goes for him. This may be typical Polypterus Delhezi (striped eel) behavior, or it may not be...he is the only striped one I've ever had.
I got the impression from owning a Senegal that perhaps they are more aggressive. But that is just my experience so far with the breed. It's just something to think about when stocking...just want to save you the heartache of lost fish.
Any bichir should probably go into a tank based on growth potential of 12". Like someone else was saying, it may not get any bigger than 8"... you really just never know. I would start, if you still want one, with maybe an albino one...either true or Palmas. I've read those are less aggressive and don't grow so large. The good thing is their bio load is not much, unlike plecos and goldfish.