I actually meant a silver arowana that is 16 inches not a tank thats that big. I am aware of how they can turn so majestically, but they easily stress out when they are in a small tank. I have kept all arowana species except asian arowanas, and by far the silvers where also most aggressive, i first thought my jardini was, but one of my silvers, thats about 19" attacked and killed my 17" jardini. Blacks are more peaceful, but can be territorial. My little 6" black hates it when a fish swims near the floating plants he loves to swim around in.