I notice that on the forum many people say that the females grow at a faster rate. I only have 1 male, all others are female, and I must say that my male grows a LOT faster than the females. Like several times faster. I got my male pewter in mid january, and he was 150 grams. It's been what, 3 months? And he is well over 500 grams already. I don't overfeed him either, 1 appropriate sized rat a every 5 days.