I have one in a 40 gal that is approximately 2 years old, I caught him and 5 others in a fish trap in feb of 2006. The fish that i have was one of the smallest but it ate pellets first, and out grew the others and eventually bullied them to the point where i put them in my fathers patio pond.
my avatar is a pict of it at approximately 6 months of age
I do not heat the tank, I feed it omega super soft pellets, hikari floating pellets, crickets, worms, any type of food. It has never turned down a meal.
the fish is very aggressive, i had a fat sleeper i was going to keep with him and it stressed it out to where it died.
my fish is probably 6" long, it may grow to 8" im not sure.
in a tank that large, i would try to put about 10 in there, add lots of drift wood, and plants to break up line of sight.