Svar från experterna! :)

Som jag skrev innan så la jag upp en fråga på forumet Betta4all om hur jag skulle gå vidare med att odla fram gula fenor. Det verkar inte vara så lätt som att bara korsa två fiskar med gula fenor eftersom det är en ressesiv gen. Så jag la upp bilder på vilka fiskar jag hade att jobba med och formulerade min fråga om hur jag ska gå till väga? Fick detta svaret från en duktig uppfödare i Holland som heter Joep van Esh. Han skriver såhär! Tyckte det var väldigt bra information och jag ska ha detta i åtanke! :)

Hi Embra,

You are right that theoretically all the offspring of your initial cross should carry the yellow trait. As yellow is a recessive trait, which seems to be a variant of the dominant red color, the color will appear red in the F1 offspring. As a backcross is not possible, crossing brother to sister for the F2 generation would defenitely give you a good chance of getting yellowfinned offspring back. The body of these fish most likely will have a metallic/dragon color on the body although this might vary between fry. Crossing the new males to one of your F1 females also can be a good option to obtain the yellow color back assuming that all the yellow fish are of the same type (it is not exactly known if there are more types of yellow or not).
Even if one of these cross does not give you yellows in the F1, this does not mean that the parent which phenotypically is not yellow, is not carrying this trait. We have to keep in mind that the percentages based using Mendelian rules usually only will be approached by performing a large number of spawns with fish carrying the same phenotype. This means that you can have spawns without a single yellow-finned fry, whereas suddenly several of these fish might appear in a second attempt or crossing the same female to another male.

If you would have the room available, I would recommend you to try as many options as possible, in order to increase the chance of obtainin yellow-finned offspring . I defenitely think you should be able to achieve your goal by working with the fish you posted above.

Many greetings,