Not sure what you are asking.
If your question is "do pet shops overstock thier tanks as compared to the recommended size tanks?"
The answer is yes & no. The individual tanks may seem overstocked, but they typically are on a plumbed system with a huge volume of water.
If your question is about the actual recommended sizes and if the fish do well in those the answer is more elusive and the reason you should never rely solely on what is recommended in any LFS. Even good ones get new employees. There is no substitute for personal research IME.
) Here's the bottom line tho, the amount of oxygen in the water determines how many fish can be put in the tank. In pet stores, usually a larger than average blower is used to supply air to the tanks to help keep the water well oxygenated. Truth is, even under these conditions, if there are too many fish in the tank, they all die. PERIOD. All because they used more oxygen from the water than there was available. So when you look at the fish in a pet store, trying to decide whether to buy them, look at their respiration rates. If they are breathing slowly or normally and swimming normally, they are fine. Don't concern yourself with the over amount of fish in the tank.
