Hi,
The regani pair have been with me for a little over two years from only 1.5". The male is a not far off a foot long, but initially at the begining i personally think they were a little slow growing. They have growth bursts, now and again. Mine is starting to bulk up more so than grow length and the cranial profile is getting steeper, hopefully turning into a nuchal hump soon.
Although not classed as truly rheophilic, regani are found in faster moving water. You don't need to blast the water with a powerhead, but for them to thrive and reach their potential, provide good clean water conditions with good oxygen content. If they except them, bulk them up with mussels now and again. Good quality dried food and that all important vegetable content.
Good Luck,
Lee.