Newbie is my tank overstocked?

[vicltruong]

sorry PH is 8.0. I guess my real question is what will happen if a tank is overstocked, assuming water quality can be maintained (i.e. Amonia and nitrite at 0) and all fish are at the same level of aggressiveness so no bullying? Is there any other factors that will kill a fish besides fighting and poor water quality?

Thanks for your help. I ask because I think 1" per 5 gallon makes the tank look very sparse and not very interesting.