Sloooowwwwww at first, after they hit 50cent size and larger they seem to pick up growth faster. I heard from my source for the watermelon that his seemed to have growth spurts after he fragged it!!?? I have notoriously slow growth in my tank anyways, which is fine but in comparison my Aquascene golden eye seems to grow twice as fast as my watermelon...but it was a bigger chunk when I got it. So I did a little experiment, I cut a frag off the aquascene golden eye about the size of my watermelon frag when I first got it and marked the date. That frag has grown faster than the watermelon for sure.