Born and raised in Iowa! Here is a post from Oddball about what stunts fish:
"Look up Brown Blood Disease (Methemoglobinemia). This is the common link of most large fish forced to live in too small aquaria. It doesn't matter how well your fish is fed. In fact, large and/or frequent meals is actually a proponent towards causing the disease in too small of a tank. It usually follows that the results of such feedings promotes poor water quality much more quickly in small and/or poorly filtered aquariums. To prevent the disease frequent large water changes are a must. By 'frequent' I mean every other day or have a constant drip system running.
Large fish in small enclosures causes rapid increased levels of nitrites. These nitrites, in effect, poison the fish's blood causing the blood cells to lose their ability to carry O2 to the body and gather CO2 for release from the body. When too many blood cells are damaged the result is a reduction of physiological processes and immunity with an eventual outcome of premature death from organ failure. The anemia is more rapid in fish than in mammals due to the fact that fish don't produce new red blood cells in marrow. Their blood cells are nucleated and self-replicate. Nitrite-damaged cells that no longer have the ability to carry O2 lose their red pigment and turn brown. These brown diseased cells do not replicate and as the disease progresses the fish loses all ability to complete simple respiration. The slow progression of the disease is the direct cause of stunting a large-growing specimen to a smaller than normal size.
"Rescued" fish can be cured of some of the effects of the disease through proper nutrition and system maintenance. But, any organ damage already suffered is never fully recovered and manifests the damage as displaying a specimen more prone to disease than specimens that never had the disease.
FYI, high nitrates in a system is also the common factor in most mystery deaths of new fish added to a sick system. It's the frog in hot water effect. Put a frog in room temp water and slowly raise the temp. The frog will die from the heat since it's body will adjust to the steady increase in temp. Drop a frog into hot water and it will reflexively jump right out. In aquaria, nitrite poisoning will increase slowly. Especially if infrequent or insufficient water changes are made. As the nitrite level increases the fish attempt to adjust to the increases even into toxic levels. Once a tank is toxic, adding new fish that haven't been forced to make such adjustments leads to rapid death from nitrite shock."
I think he must have forgotten the primary cause huh? Seeing the tank walls? Feeling claustrophobic? But he probably doesn't know anything either.
Wasn't much of a debate, but I do sincerely wish you good luck and happy times with the puffer. I love mine.
