Hi, to answer your question. I have a Common/Sailfin Pleco and he has grown 9 inches in 9 months. He is now 12" I bought him in May last year. His growth rate seems to be fast as I have read of others which have not reached his size in 2 years. I think it is probably a case of wait and see I'm afraid! I do overfeed my fish a bit so perhaps that is the reason he has grown so quickly. Hope that gives you some idea. Mine is my favourite as well.