Humminbird fish ID Fish size

Always wondered how big the actual fish are that so up in fish ID on the humminbird so I did some research and here is what thy say.

What determines fish size?

This question is very difficult to answer as there are various factors that affect the readings such as the size of the air bladder for each fish species and the density of the fish species. The fish sizes can roughly be determined as:
Freshwater species - Small - Baitⁱ to 1 pound, Medium - 1 to 3 pounds, Large - over 3 pounds

Saltwater species - Small - Bait to 5 pounds, Medium - 5 to 15 pounds, Large - over 15 pounds