just popped into the LFS which i brought my 3 RBPs from in November and they still have 1 left from the batch i got mine from. my 3 are approx double the size of the one still there. strange to see the big difference. asked the LFS guy about the main causes and he said that stress can lead to them not growing very quickly, also he said the rbp left in the store only eats every 3 days, thought that when they were still young they should be eating everyday? anyway, its good to compare them to see how well mine are growing!!