They grow very fast to about half their size and then slow down I think, just like clowns. I have 4 and they have grown about 1.5" in 3 months and are now around 2.5-3"
wots max size clowns grow in aquariums??? i seen 12" on forums and home page index, but been told usually stay bout 6-8" in captivity which mayb why they aint been bred yet not sufficent numbers anyway.
Both The Wolf and I have "Yo Yo" loaches, (Pakistani Loaches), at 200mm/8". The growth rate is pretty much as stated above, to about half size very quickly, then slowing down. My biggest is almost 210mm now and has been in a 6x2x2 with 3 others for ~5 years.