When the filial term was first used, F1 referred to the first filial generation seeds/plants or animal offspring resulting from a cross mating of distinctly different parental types (F0 X F0 = F1). Fish hobbyist applied this system to fish, assigning F0 to wild caught fish and F1 to the offspring of a cross between two unrelated wild caught fish. So depending upon ones interpretation, F1 could be the first generation of a cross between two wild caught fish or it could be a cross between two distinctly different parental types. Thus there is much confusion. But as far as I am concerned, I could care less. As long as the fish I breed produce good fry, who cares what generation they are. They can be F1 or F1,000. All that matters to me is how the fish looks.