Here is a spin on things that I'd like every fish keeper everywhere to realize. When we put fish in tanks, we are preventing them from living a natural life. Things such as flooding, rain, drought, finding potential mates, predation, parasites, and the ability to take over potential territory. Keeping any fish in a glass box, rubber lined pond, or concrete raceway impedes the fishes ability to live naturally. Our ethics in keeping the fish as happy and healthy, is most of our goals in this hobby. Education is the best way to open peoples eyes in this situation. We can all make suggestions as to what we feel should be done with certain fish to keep them happy. But fact is there are fish available in the trade that shouldn't be there because there are far too many people that don't care to provide adequate conditions. Now on the other hand, We all like fish on this site.. That being said everyone on this site is responsible for a fish living in an unnatural environment. And a lot of large or aggressive species, but most of us are trying our hardest to accommodate them in the best way. I have several pacu and 2 redtail catfish that outgrew someone else's system. I have a bigger tank and for now they are "happy" there. I never would have bought these fish personally but am taking strides to give them the best life I can provide.
To the op and others who read. if you like gator gars, or other large fish accommodate them. If you don't think you can, reconsider the purchase.