I saw the arowana in a tiny tank, I put it in my 75 gallon. I will think about upgrading but I see so many people having this combination in a 75 gallon and in a 55 gallon too. Mine is a jardini, not a silver, it doesn't get to 4 foot.....it's the smallest, it is also fine keeping it in a 75 gallon. The clown knife too, at the most they could probably get to 20 inches but kept well, even bigger. A dwarf goonch is only 10 inches long, but fine....I will not choose to keep it. In my LFS they kept it in a tiny tank less than 10 gallons......I'll just stick with a target fish. I will go back to the target fish thread. If you are gonna call me a troll, nevermind.