Obviously inbreeding is a vital tool in any artificial breeding regime, but just how susceptable are guppies to deformities and lack of vigour? And at which point is an outcross recommended?
Cheers

I have read that they can go for as long as 18 generations before seeing any loss of vigor or size... also that outcrossing should be avoided unless you need to... I don't understand that part... but hey, that's just what i read somewhere!
~Krys <_<

Thanks Krys

The idea behind a good strain is this:

You get a strain pure, it should take a minimum of 10 generations of selective breeding.

You then take the fry from the last genration, which are now pure strained, and split them in half, you keep each of those strains of guppys seperate even though they are exactly the same strain. Generations down the track everything should run smoothly, then one day you see deformitys or size change, or finiage problems, so thats when you outcross. This can often lead to wierd colour formations and finiage but with a few generations of selective breeding you can get the strain back on track.

Shae

But you can also "outcross" to other seperated strain that you already (you established two genetically linked but seperate strains didn't you?) have if the
generations are far enough apart. You might even end up with some hybrid vigor.
A minimum of 8 tanks per line is needed - usually more. Only outcross with a genetically new fish as a last resort. It will take at least 3-5 generations past that cross to recover all the lost genes. Some of the best may be lost forever. :hmm: