While ago I bought a female JD that was stunted from Wal-mart, she would breed, but would only lay 25% of the eggs that one would expect, her fitness was greatly reduced.
In perfect water, with adequate water changes and feeding nothing ever changed. She grew, but much slower than the male did, while it was clear that the "stunting" did have an affect on her and I could still get her to grow and be happy, the damage had been done. IME you can prevent further damage, but not reverse what has already been done to any sizable extent.