My Clown Knife lives with a Florida Gar, Lima Shovelnose, Jack Dempsey, Two Tinfoil Barbs, a Pleco, and a Albino Channel Cat. Everybody gets along good!
once i had a CK which was the same length as the arowana but slightly bigger in girth. the CK kicked the crap out of my 2 year old arow! it took ages for the fins to grow back. ure choice man but i wouldnt wana risk it :s maybe a jardini might be able to defend itself.