Originally Posted by
Nonn
snip...
One question, when you have only 2 original pairs, how do you manage the line? Keep the line separate as long as the offspring doesn't show sign of defect, then cross them, or mix them up from the very beginning?
It depends on what you wish to do. To keep the most of the original 4 sets of genes, mix and match early with different pairs for each brood. If a bad recessive shows up, you can usually figure what lines carried it and eliminate it by future selection of breeders. The earlier you do this, the better for the hobby, IMHO. Keeping lines separate could hide a negative recessive for many generations.
If the original set shows high variability, and you suspect a hybrid could be involved, line breeding (offspring to parent) and severe selection may be needed. This can, potentially, reduce the unwanted hybrid genes toward zero if done carefully.
IMHO, this line breeding is needed for most commercial imports of killifish from Nigeria and surrounding region. The exporters are most careless about getting the right females with the right males. I doubt if it is a deliberate attempt to make the strains essentially sterile (though it does in a generation or two). They don't seem smart enough for that kind of clever merchandising. [Most of the folks from there who are above minimal intelligence seem to be occupied in running 419 scams. ]
Wright
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