is the rule of inches of fish per gallon one inch of fish per five gallons? Thats what I was thinking. Could someone tell me if i am right or wrong? And if i am wrong please tell me the correct rule.
0.9cm of fish per liter for small fish, 0.74cm of fish per liter for medium fish and 0.58cm of fish per liter for large fish.
HTH
EDIT
These are only reference values. The maximum number of fish depends not only of tank capacity but also of several other variables such as filtration, water changes and fish species. You should always check the ammonia/nitrite/nitrate levels to be sure you don't overpopulate the tank.
Inverts increase a tiny amount of bioload on the tank when compared to a fish. If you look at reef tanks you can see that most have corals and other inverts so closely packed together and yet they have to monitor their fish closely. This is due to the much higher bioload that fish produce. I dont think you can overload a tank in bioload with inverts alone