Right nutrition at the right time.

If an adult person is 6 ft and 250lbs and then starves down to 150 he is still 6 ft.

But if he is born with the genes for 6 ft but as a child gets starvation rations he may only grow to 5'5 due to lack of bone growth .

We have discussed the potential for stunted fish. I will try to find it later. IIRC if conditions for growth improve then growth will resume but they will never reach their genetic potential ( as they would in a balanced /fertile pond). The question becomes are you better off starting over or just reduce the # of stunted fish and move on. If it is a temporary food shortage I would not start over but would fix it as the situation would not have effected their genetics. However if it is a longer term (several generations of stunted fish) situation where the possibility of stunted fish genes or conditioning may exist then it is a different call for me.