For the fishes best interest, dont buy it. If you want to keep it into adulthood then a 5000 gallon pond would be a must. Which I highly doubt you have.
as for the truth ... i had a white sturgeon go from 3" to 7" in about 3 months ... feeding bloodworms 2x a day ... and that was in a 29g tank
as for growth rate on sterlets, i will let you know, mine are only about 5" right now
if you have a pond to put them in, go for it!
obviously they need cold water, and decent aeration, other than that they are great fish!!!
I just wanted to say that sterlet sturgeon are awesome. Hopefully I will get one soon for my indoor pond which I will soon make out of portable frame pool .
I have one in a 45 right now, havn't had it long enough to notice any growth so far but its an awesome little fish. As long as you have a pond with good aeration I bet a sterlet would love to have a good home.
sterlet sturgeon if kept right will live 25 years+, so as far as getting to max size i would say a very long time 10-15 years. http://en.wikipedia.org/wiki/Sterlet
my 2 sterlets have put on an inch in the last 3 weeks ... from 5" to 6"
feeding 1-3 times a day on bloodworms
i am going to start looking into pellets for them in the near future ...