My advice is keep other fish with him, if you are, bigger around than he is, and/or just bigger longer or fatter. They eat fish their size if they get to hungry. So keep him fed and away from hunger.
Not at all...I am now on my third and I told myself final armatus.I have not done one thing different with my previous payara (red tail tats also)except feed them smelt which I now think has to have had something to do with them all dying.My current big boy only eats tilapia,catfish and raw shrimp.I have never given him smelt and he is over a foot long and going strong after about two years.