It all depends on the individual fishs attitude in my experience. I have actually had 2 x 11+" leopardus together in a 75 for quite awhile. Dont get me wrong, this was less than ideal and am not suggesting that anyone do the same. But these two did fine for several months. A buddy of mine is actually hanging on to one because I dont have room for both and cannot get a larger tank at this time. And since it was asked to share some pics....
Its about 12" now
I just lost my l114 last week. No idea why. I had him for about 8 months and just randomly found him belly up. If i knew how to upload pics from my iphone id share my l273 with everyone.