First of all, it is not 1" to 1". It is 1" to 1 gallon. That is 1 inch of fish for every gallon of water. Meaning if you have a 55 gallon tank, you could have 55 inches of fish. But the 1 to 1 rule is for fresh water. Saltwater is 1" of fish for every 5 gallons of water. So theoretically in a 55...