Yay! Well done 
It's not so much that high nitrate stunts growth, it's more that many fish produce growth inhibiting hormones which will stop or slow their growth once they reacg certain concentrations (this is, of course, where the wretched' fish only grow to the size of the tank' myth comes from).
Tanks with high nitrates are, in general, ones that aren't recieving enough water changes, which will also result in high concentrations of the hormones.
It's not so much that high nitrate stunts growth, it's more that many fish produce growth inhibiting hormones which will stop or slow their growth once they reacg certain concentrations (this is, of course, where the wretched' fish only grow to the size of the tank' myth comes from).
Tanks with high nitrates are, in general, ones that aren't recieving enough water changes, which will also result in high concentrations of the hormones.
