Question about how many fish to have in my fish tank?

Many places will tell you the 1 inch of fish per 1 gallon of water rule, but this rule or guideline is ridiculous. Would a 10 inch pleco be ok in a 10 gallon tank? Of course not. A better rule of thumb would be 1 inch of fish for every 3 or 4 gallons of water (this is a freshwater guideline only, saltwater fish need even more water) with even more water volume per inch being better.