Hey, this looks like the thread for me.
I've been lurking on MFK for a few days, lots of good information for a fish newbie like myself. I found the side after doing a search on how to construct a larger tank.
I have a male GG that's about 18" long in a 75gal tank, the filter is a Rena XP3, and the whole setup was given to me by a sweet old lady that could no longer take care of Gussy. Food consists of whatever fruits and vegies we're eating. When I make a salad, Gussy gets the trimmed off lettuce pieces, and he'll much on apple cores, blueberries, over-ripe banannas, and such. It's about like having a vegetarian pig in the water.
With the exception of a crayfish that Gussy seemed more than curious about, there's never been any aggressive behavior towards the occasional goldfish or chinese alge eater that's been in there with him. Get near tank, however, and you'll get a good look at the inside of his mouth, as the innumerable scratches on the inside of the acrylic will attest to.