Yes, the females usually grow faster. For instance, I have a pair that are about a month old and that are from the same spawning. The are both good eaters but the female is at least half of an inch bigger already. The is no exact growth rate as there are so many factors that determine growth (gender, genetics, what they are being fed/how often/ how much, supplimentation, temperature, humidity, etc.). But overall the females usually grow at a faster rate and reach their adult size faster.