Refer back to: Hamburg swordtail inbreeding Dr. Gentzsch started with a colony of 5 Hamburger swordtails, all clear fin. According to some source of info, that time, Hamburg was maintained in heterozygosity by crossing to X. Helleri. That explained the fishes having clear fin inherited from X. Helleri. Assuming Wild gray/green color is the background of wildtype X. Helleri; the genotype could be coded as [StSt] (St: Stippled defined by Dr. Gordon); And Hamburg trait, the Black scale fully cover the fish body, was encoded as [S/S] (S for Schwarz means Black in German); So, the Heterozygousity of Hamburg that Dr. Gentzsch used likely has [S/s St/St] form. Red swordtail was introduced to Hamburg lineage later in 1975 using Red female x Hamburg male. Mentioned in his article, Red males born from the cross, implying that Hamburg could be dominant. Rather, Gray / Green background was affected by Red, throwing Red offspring (Red is dominant to Gray / Green as we know in Brick red form). This cross could be encoded as: Male: [S/s St/St -/-] x Female [-/- St/St R/R] = [S/- St/ R/-] for Red Hamburg; [s/- St/- R/-] for Red assuming with ratio about 1:1 resembling parental types. Also, following Mendelian law, dominant Hamburg by two heterozygous parents would likely expect a result 75% Hamburg in each generation. By doing inbreed F1 from the above cross, there’s likely a chance [St/ R/-] x [St/ R/-] give raise to 25% green swordtail [St/ -/-(r/r)] in the next generation. Confirmed from his work, Dr. Gentzsch said “number of black fish on total ranged from 64.2% to 80.4%, means ratio is 71.5%” close to 75% and “the Red and Green swordtails isolated from Hamburg parents reproduced only Red or Green offspring” would means they are recessive in Hamburg model. Now, how Red Hamburg looks like? Will Red dominate all over body and well established under layer of Hamburg pattern? According to Dr. Gentzsch, he experienced as following: “Most black offsprings in the 18 generations had clear finnage and only partially had a reddish fin staining” Could it be the case that Red was heterozygous, and their pigmentation expressed not strong enough to show vivid appearance. Also, the expression of Red color on swordtail could be regulated by a group of genes thus lacking one or two gene from the full set would likely bring down significantly the expression. Those extensors have a chance to group together again if practicing inbreed and selection over generations.
Here is another picture of beautiful Red Hamburg done by Antacarol, Indonesian breeder.
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