Not all sturgeons need cold water, adn not all sturgeons grow large. There are
a coupl of species that grow no larger than koi. the sturgeon you are most
likely to find for sale would be the sterlet. Nice fish, grows to about 49"
long and is peaceful. I't feeds in much the same way as koi but not as
agressively. You might want to teach it to eat pellets in a seperate tank until
it gets the idea and the size to compete with koi.

Moon
remove nospam from e-mail to send to me, I grow trees in aquariums like bonsai.
I breed dwarf crayfish, great for planted community tanks. If you can get me a
shovelnose sturgeon fingerling (Scaphirhynchus platorynchus) no wild caught
please, contact me