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Fin Length Genetics

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Finnage Length

The original wild form of Betta Splendens has short fins. Longer finnage is a surprisingly dominant mutation that has been developed over many years by breeders worldwide to produce the different fancy tail types you see today.

Ever wondered what you would get if you crossed a ling finned Betta with a short finned one? Look no further! Keep in mind, the following charts will only determine fin length, not tail shapes (HM, CT etc) that is determined by other genes.

Genetics Terminology:

Dominant: If a Betta carries a dominant trait, it will display this type NO MATTER WHAT it is crossed with.

Recessive: If a Betta carries a recessive trait, it will only be visible if the Betta inherits one copy of the recessive trait from each parent.

Genotype: Describes the genetic makeup of the Betta. For example, the genotype for a pure short finned betta would be llll.

  • Pure Long Fin: LL
  • Pure Short Fin: ll
  • Short Fin Geno Long Fin (long finned Betta carrying one copy of the short fin gene): Ll

Pure Long Fin x Pure Short Fin

LLxll_zps6096d0e2.jpg

100% Short Fin Geno Long Fin

Short Fin Geno Long Fin x Short Fin Geno Long Fin

LlxLlMix3_zps38681db3.jpg

25% Pure Long Fin

25% Pure Short Fin

50% Short Fin Geno Long Fin

Pure Long Fin x Short Fin Geno Long Fin

LLxLlMix_zps05e4e2ad.jpg

50% Pure Long Fin

50% Short Fin Geno Long Fin

Pure Short Fin x Short Fin Geno Long Fin

llxLlMix2_zps49202adf.jpg

50% Pure Short Fin

50% Short Fin Geno Long Fin

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Excellent work, J - but can I refer to the article BETTA GENETICS PART VI By GENE LUCAS, GIAA where he states:

The long-finned variation is obviously not normal, even if it has been in existence since before Bettas were introduced into the western world. Though it is quite variable in expression, it is rather easy to determine in most fish …it either is the long-finned type or is not. It was investigated and reported on briefly by Eberhardt (1941) who suggested the genetic symbol P (for the German "pratchtig" … which roughly means "splendid"). The symbol seems to me to be the most appropriate so I do not suggest a change. I have crossed long-finned domestic fish with short-finned wild types and I got long-finned progeny in the first generations. I was able to get short-finned type in F2 crosses (brother-sister matings from the above spawns). This indicates that the character is inherited and inherited as a Medelian dominant to short (or normal). This agrees with Eberhardt’s report.

So, should we be using P for long fin and p for short fin?

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Thanks for the info. I couldn't find any reference online to symbols for fin length back when I wrote the article. Will make the adjustments when I get the time to redo the graphics.

Yellow-Icon_zpsac250c40.jpg

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All good mate - you know me, research lots on the genetic side and luckily some of the info stuck.

I knew it was around somewhere, but I did have to go off and reread a few articles to find it :)

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