JKS3613 and scott69 those are both normal type results with your conditions for good quality F-1s. ASF has good fish as do others and I have experienced the same results you report with their fish and those of others as well. The 6 inch fish is likely one that has the genetics to have quick growth. All of them will not exhibit this growth. In addition growth slows as a % of body weight over time. A 1 inch LMB grows at a very high rate but that growth slows proportionally as it gets older.