I have a soft soft for Fahaka Puffers (tetraodon lineatus which are freshwater, get pretty big are are very, very aggresive & preditory.
But then all species of puffer are preditors and should not be kept with anything you would mind losing, even the so called 'peaceful' species like South Americans can become suddenly aggresive without warning and wipe out their tankmates overnight.
It's only a matter of time.....