Why Is It The 'done Thing' To Breed Sibling Pairs?

[Tolak]

Most bettas you see, like angels, are far removed from their wild ancestors. F0 is rarely used, the term wild is more often used, as in "wild caught angels" Wild fish are generally more difficult to breed, as they are more demanding in regards to water and diet. This makes anyone involved with breeding a certain species very interested in F1 wilds, as they have completely new bloodlines, in a fish that has been bred domestically. These are generally less demanding than wild caught fish.

F2, F3 etc. is generally used by a breeder to keep track of a certain line. Each successive number is an inbreeding of fish, and as mentioned, once you get beyond F5 with many species you may see a reduction in some other aspect of the fish. This is why breeders trying to fix a certain trait will get multiple lines breeding, and cross lines to reduce or eliminate inbreeding.

The F system is designed for one line of fish, and does not take into account outcrossing. There are many systems used, and most are probably individually created. Here's one explanation of how to keep track; http/www.angelsplus.com/ArticleLinebreeding.htm

 

[LauraFrog]

The other thing that you have to take into account is that fish are expensive. You can't just buy in loads and loads of unrelated fish, make breeding crosses based solely on what the fish look like at the time of breeding, and hope that a percentage of the spawn is usable. By crossing siblings, at least in F1, you can see what the line is throwing (and so detect the genes that are hidden in it and will generate throwbacks) and also pick out the fish that display the trait you want to 'fix' most strongly. Then you can start bringing in other fish from other lines.

If you start off with a totally unrelated pair, you don't know the total genetic history of the fish. There are probably recessive genes on both sides that are being masked, and that will cause 'throwbacks' to other colours and fin types. You also don't know which genes are causing a particular trait that you are breeding for, as a lot of them are controlled by several genes, and so mixing two fish that LOOK the same may result in totally unsatisfactory results. Of course, breeding totally unrelated fish together is great fun, and this is often how ideas for new lines get started. But it's not good practise, because of the difficulty of rehoming the fish you create if, as often happens, they throw back to veiltail in an uninspiring colour pattern.

A lot of the betta strains we have today were the result of one mutation. One 'odd' fish that stood out. The halfmoon (and superdelta, and delta - every large-finned symmetrical strain) is based on a single fish. Yeah, one fish. They made the strain by breeding his daughters back to him, by breeding brother to sister, etc. And although the halfmoon is generally less vigorous than the wild strain (which nobody would dispute) there's certainly no problem with them inexplicably dropping dead left right and centre, and it's still THE prized show strain. There are a huge number of colours and markings now associated with the HM, and the original line was blue. To introduce new colours and markings onto this new finnage type, also required an enormous amount of careful linebreeding. It's the only reliable way to fix genetic traits. Yes, there are disadvantages, some of them serious. This is evidenced by what unscrupulous breeding of pedigree dogs has resulted in, in some lines (hip dysplasia, dogs that cannot breathe normally/give birth unassisted, etc.) But careful linebreeding, paired with diligent record-keeping and note-taking, is the only way to go about maintaining fancy strains.

 

[lilacamy931]

welldone Laurafrog that is how I understood the breeding lines, etc. I don't necessarily agree with it (well in dogs I certainly dont even to get pedigree) but it is the way it is done. I do find the process really interesting though, perhaps I could follow a line later.

 

[Curiosity101]

Thanks laurafrog for your detailed response.

I'm fully aware of the genetics behind this.

My point was that, nowadays, you can argue that inbreeding isn't neccesary. As the traits are already fixed and have been bred many times. You can breed un-related fish, with similar physical traits and colourations (so long as you have both fishes history), to achieve the same results. Unless you're trying to develop a new tail type, colouration etc etc.

Anyhoo that then led to the question as to why it is the 'done thing' to still breed sibling pairs.
You did point out that 'good' breeders keep detailed records, do not go past a 5th generation, and there is no markable difference in the health of a wild specimen and a line bred specimen.
I just can't agree that for general breeding, as opposed to developmental breeding, you can justify breeding sibling pairs.

Whether I agree or not I'm happy that my question has been fully and thoughtfully answered so thank you everyone

 

[Blondie_Kate]

I think im now just confused too many F's me thinks