You can't always judge a fish by it's size. I have a 4.5" FH sharing a tank with a 3.5" Managuense; and the managuense gives the FH all he can handle. Soon they will have to be separated as the manny will dominate the tank. (jmho)
i retract my former statement, i moved and my GT is thriving like a mo-fo, its been about a month and it not only had a growth spurt, but some real color is starting to show and its getting some attitude all the sudden