The inch per gallon and fish growing to the size of the tank are probably the two biggest myths in fishkeeping. The inch per gallon can sometimes be used as a guideline, but its not the be-all end-all rule. By this rule, 10 one-inch neons would have the same bioload as a single ten-inch oscar. Simply not true. As fish get bigger, their bioloads to not increase in direct correlation to their length. You just have to use common sense, and think about the fact that if you over stock you're going to either have to get rid of fish or do 3-7 water changes a week.
The other one is also not true. If you're keeping an archer in a 10gal tank and it stops growing after 3 or 4 inches, its stunted. There is a lof of speculation about what exactly causes the growth to stop, but in any case its not natural. So, there's some food for thought I guess. When I choose fish to go into a tank I look more at the footprint of the tank instead of the volume. Like a 55gal tank is a very common size, but its only 12" long. Some fish might be good in 55 gallons of water, but if they get much about 8-10", the tank is barely wide enough for them to turn around. In short, there are a lot of things you should take into account when choosing fish for any aquarium.
The other one is also not true. If you're keeping an archer in a 10gal tank and it stops growing after 3 or 4 inches, its stunted. There is a lof of speculation about what exactly causes the growth to stop, but in any case its not natural. So, there's some food for thought I guess. When I choose fish to go into a tank I look more at the footprint of the tank instead of the volume. Like a 55gal tank is a very common size, but its only 12" long. Some fish might be good in 55 gallons of water, but if they get much about 8-10", the tank is barely wide enough for them to turn around. In short, there are a lot of things you should take into account when choosing fish for any aquarium.