Whats the F5?

Found a gray banded kingsnake I’m interested in and the description says it’s an F5 female. I grew up in tornado country and an F5 ain’t good news. What exactly does THIS F5 mean?


I would probably ask the seller to clarify. With some animals, the F number refers to how many generations it is from the original breeding.

1 Like

Usually if the animal is a cross breed the term F something is used.
For instance dogs, Labradoodle F1 to another labradoodle F1 would result in F2 offspring.
To show the second generation is ‘pure’ labradoodle, from pure labradoodle parents. :blush:

1 Like

The F stands for filial…(might have misspelled). It’s sometimes used for mammal hybrids such as Bengal and Savannah cats for example.

Using savannah cats as an example the original hybrid cats created from the original servalXdomestic cat cross would be labeled as F1 being 50% of each. As @ghoulishcresties stated taking 2 F1s would make F2 and so on.

Never heard it used for a snake but I’m guessing as with mammals it would mean its 5 gens removed from a hybridization.


As said it’s the number of generations. You might want to ask if it’s 5 generations in their group, from when they have lineage, from the wild, etc.

1 Like

Well that makes more sense. Armed with that knowledge I’m betting he’s 5 generations removed from wild caught. It’s a pretty specific locale.

Many thanks, yall.

1 Like

Yep, you’ve got it! When you’re dealing with rare locales or species that are normally only available wild caught, F1/F2 etc is more commonly encountered.

A higher F number means that it’ll likely be better adjusted to captivity (less likely to insist on lizards as feeders for example).

The F5 you’ve found is probably the offspring from the best adjusted, best feeding, best growing examples from the previous generations.

If I’m successful in breeding my wc sunbeams, black African house snakes, African egg eaters or brown Kukri snakes, their offspring will be F1 CB. I’d keep the best ones back for breeding. Their babies would be F2 CB.

The only “drawback” from a higher F number is that it’ll likely be more “inbred”, but so long as the healthiest and best babies are being kept back for breeding, it becomes “line breeding” towards health and ability to cope with captivity.


He would most likely be a pet only at this point. Unless I can find a female of this particular locale.

Again, thanks @kukrikeeper .

Additionally, proper outcrossing is the best way to get “new blood” into a population and limit the effects of inbreeding.

1 Like

You can always buy an F2 from another keeper to breed with your own F2 stock and still produce F3’s.

I’d like to know how the F system would work when breeding an F2 to an F3, or a multi-generation captive bred animal of unknown but high F number to a wild caught animal. Or does it just no-longer apply in these circumstances?

1 Like

I don’t know the specifics of it but it probably is important to know the F. Maybe someone that works with the system more can add to this thread. I would like to know also because I hope to work with less colubrids.

1 Like

From a Savannah cat page. I know it’s important in the UK to know how far removed a Savannah cat is from a Serval as I think you need a DWA (dangerous wild animal) license for a Serval and F1, F2 and F3 cats. I think F4 counts as outcrossed enough to be considered domestic (edit: I just checked and you don’t need a license for F2 Savannah cats and upwards). I’m sure it’s similar with Wolfdogs too (edit: I just checked and you don’t need a license for F3 Wolfdogs and upwards).

So by this logic, if you bred an F5 kingsnake to a wild caught Kingsnake of the same locale, you’re back to F1.


I’d like to know this as well, as this is an F5 snake. Or, how many F’s before it doesn’t really apply any more, if that makes sense.

That answers my question! Guess we were posting at the same time.

It would be interesting to get to go out and find these wild caught snakes, too!

I wonder how high the F generations are for some multi morph cornsnakes or ball pythons, I bet they’re high from stacking mutations.

Thanks for the graph. It always helps to have a visual, in my opinion. Definitely made me understand.

Probably like F+20