Line Breeding

[FREAQ]

Could someone give me a quick outline on what line breeding is?

[YeW]

Line breeding is artificial selection (at least in my book).

It is selecting the best stock (whether it be lemons, dogs, fish or cattle) and breeding from the best offspring, then selecting the best offspring etc and down the "line" you go.

It requires a degree of inbreeding (breeding to closely related individuals) and outcrossing (breeding to less related individuals).

You'll find some ppl opposed to it on the forum. I am not - as I believe in many cases nowadays we are inadvertently "linebreeding" for the largest and most aggressive males (and not necessarily those males with the best colours) anyway.

HTH -

[John McCormick]

Hey Yew,

Doesn't sound quite polite enough does it.

Anyway just thinking about what you just said about breeding the best with the best etc, etc, etc.

It is not always the the best of course that is chosen, quite often it is what is the desired trait that is selected instead, same only different?

Just another thought on the line breeding in our case (with fish that is) what you end up with may not resemble the original wild specimen at all, in colour or finnage or what ever the desired trait was that you were looking for in the first place.

Is this good or bad?

I suppose it is open to debate.

Regards

John.

[YeW]

True enough John -

What linebreeders consider to be the "best" trait isnt always the case. "Selected" is much better. I'd like to think fish line breeders select for a variety of traits not just one.

You only have to look at the dogs to realise how badly linebreeding can affect animals (eg: bulldogs ).

[griffin]

The problem as I see it is this - we can't replicate the environment from which our fish came in every detail. In particular, no matter how hard we try we'll never be able to breed our fish in all our seperate little tanks all over Australia in the same way that nature does in the lake (or river etc) with natural slection. No matter what we do (even if we do try to emulate natural selection) when it comes down to it we're linebreeding in some way.

So if that's the case we might as well put a bit of thought into it and try to line breed for something better rather than doing it haphazardly. Or you can even linebreed to try to keep the fish looking like the wildcaught ones - I think that's the aim of most of us who care about the quality of the fish we breed.

It's true that linebreeding can result in big problems - you can just as easily linebreed for bad as you can for good. Bulldogs are a good example - but don't get me started on what's wrong with them (and all as a result of poor linebreeding) as this post will then fill several pages! And there are many other similar examples in the dog world - but by the same token I have also seen how a bit of effort on the part of dedicated breeders has resulted in many breeds being "saved" from the genetic faults that had crept in.

The point is, fish breeding is not as simple as getting a male and a female to produce fry......we really need to think carefully about which males and females are producing fry...and which ones should not.

Cheers,

Jess

[Rol&Jas]

As the others have mentioned before the line breeding is selective breeding. Goldfishes are very good examples of linebreeding. The ancient Chinese found some wild carps that had a few yellowish scales. By selecting these fishes carefully and interbreeding them they came up with the yellow or gold coloured carps (goldfish). Unfortunately line breeding is not always beneficial to animals, in the example of goldfish they would be disadvantaged in the wild because of their conspicous colouration. I am personally disgusted of most gold fishes as breeders find the beauty????? in the most grotesque and deformated formes (YAAAKKK), like the ones that have popping eyes or triple fins, lion heads etc. These fishes are also more susceptible to diseases and most of them can hardly swim.

If you selecting fishes by their good traits and not defective traits you can actually breed out much nicer and tougher generations of your fishes. Any of us who cares about the quality of our fishes does selective linebreeding in a way as we select the nicest looking and healthiest fishes for breeding.