There tends to be some confusion as to the proper notation to use when selling fry. Some people use the notation F1 to indicate their fry are offspring of wild caught parents, while others use G1. So which one is correct?

While the filial notation is often used (F1, F2, etc.) to indicate generations from wild caught parents, it is not the correct usage. The F notation refers to any line breeding from any known parents. It is generally used to calculate the inbreeding coefficient. In other words, it is used to keep track of how many generations inbreeding has taken place for within a line. So if one were to take two fish and breed them (P1), their offspring would be F1, the offspring of that generation F2, and so on. Anytime breeding goes beyond F3 or so, the risk of inbreeding depression tends to increase fairly quickly, and breeding more than 3 generations within a line without outbreeding should be discouraged. Inbreeding coefficients can be calculated for outbred populations as well, but are difficult with aquarium fish.

Generation (G) from wild notation is essentially the same but is reserved for lines bred from wild parents. So wild caught parents would be referred to as WC, their offspring as G1, and so on. Most experts consider G1/G2 as the farthest this notation should be carried, as beyond that, the line can really no longer be considered wild. As well, the same note as above regarding line breeding beyond 3 generations applies here.

So, to summarize:

• If you know the parents are wild caught, those fish are referred to as WC
• Fry from WC parents are known as G1
• Fry from G1 parents (one generation inbred) are known as G2
• If you have two parents of unknown lineage, they can simply be referred to as Tank Raised
• Fry from any set of Tank Raised parents are known as F1
• As with G2, fry from F1 parents (one generation inbred) are known as F2