Back to matters, they are an inch long, they will be absoulutely FINE in there for a while.
RTW
Not that
I know
anything about
koi - but they will not be
fine, as you put it.
RTW, I raise koi, it's pretty much my life - besides raising my own children. I would never place any of my koi babies (yes I breed them) in such a small amount of water. From the time koi hatch to the end of the their first year they should be between 5 to 8 inches long and look 'robust'. Their first year is an important steping stone towards being a healthy koi. In the first 4 years of their lives, every year they should double, if not more, their length while adding to their girth.
What you are doing is cruel, you are upsetting the natural order to which these wonderful fish NEED to thrive. Koi are not guppies, they are not tetras, they are not fish limited to growth - they continue to grow throughout their lives - and you just took 3 koi and placed them in a tiny glass house - placing restrictions on their growth and health. You haven't a clue...
You don't get, I don't care... fools will be fools. I do care about the koi - and they will teach you a thing or two if you keep them in that aquarium... and then you might, just maybe, realize that you should have taken the advice and caution offered to you.
Can't believe I wasted 3 mins typing this...