f simply stands for filial, as in a generation of a family. like youre a 3rd generation, your father is second generation and your grandpa is 1st generation. depending on where you start counting. your fish is f-2, it simply means it descended from the first generation that the farm started on for breeding this certain type of aro. this makes your fish a second generation of the type of arowana breed from your farm. most certificates declare what generation your fish is from the first captive bred individuals in their farms who were in turn, descended from the wild. like mine is certified to be F3, 3rd generation fish descended from the first batch of captive bred aros in the farm where i got it. dont worry, it does not matter with regards to the price and value of your fish. its just mandatory by law that farms declare their fishes to be from captive bred individuals, not from wild ones