According to the guy that sold me the 21" lap at the time he said it took him three years to get that size from 9". He only had it in a 150g and I was surprised it grew so fast. I'm hoping they'll hit a growth spurt from eating tilapia. I'll have to put tilapia feeding on hold this week since I'm running only on one filter cuz I snapped the double tap valve on the canister during maintainance.King-eL;4407989; said:It takes time. I notice that 12, 14, 16 and 18 is where they slow down in some point and then a sudden burst of growth. May take many years though.