Tiger LMB - female Flas selected for fast growth X male northern LMB selected for aggressiveness can grow fast - a lot faster than the averages from the studies. The numbers Bill gave for Greg's observations are good but you can experience even faster growth than that. Some that we stocked at 8 inches grew to 4 lbs at 16 mths and 10 lbs at 3.5 years.

Note that one possible explanation for the different sizes , in addition to the shooter concept already noted, is the fact that fla LMB males are much smaller than the females. Because you are using F-1s (half fla/half northern) that genetic trait is in play and can effect the size differential between males and females. I have seen F-1 males at 3 be 1/3 to 1/2 the size of the females.