They grow to 10" and grow insanely slowly. (cichlid wise at least) Nothing will work with a gt in such a small tank besides dithers (giant danios would look nice) or a pleco.
LOL I posted almost this exact thread a little while back. I've been thinking about a JD. . . upgrade in a year or two? Anyways, I have rainbows with mine. I figure when the rainbows get big, it will be a REALLY colorful tank.
gt's are a species fish... dont put cons with them!!! please everyone stop saying cons go with other fish they dont..... if u want your jd's and cons to fight keep it to yourself... gt's are not aggressive in most cases jd's are regularly more aggresive... imo all three cons jd's and gt's are species fish as are all large ca/sa cichlids.... cons are smaller and have always been thrown in with anything... what would go well with your gt right now is a female... u can breed him now for a little while in the 55 with good water the female should take to him and u might get lucky before your upgrade.... no pleco no corys no dithers.... go with a female they will be much more pleasing to watch and easier on your big guy good luck
My GT is only about 3 inches right now but he is most definitely the most aggressive fish in my tank at the moment. He keeps busy chasing my convicts around most of the time. They are half his size but not a fin has been shredded yet.