I bought a couple of bags of green swords at the ALA Convention in Indianapolis. I know next to nothing about swords. I have two questions:
1) One bag that I bought contained spotted green swords. Can anyone tell me what the typical pattern is on fry of this type and how the pattern changes over time?
2) Another bag that I bought had a few fish with high fins. Can anyone explain the genetics of high fins in swords if it is relatively simple, or point me to a good reference where I can read about it in detail.
Speckling on the swords is a dominant trait, as are all melanic mutations. They aren't likely to change much if your fish are more than a few weeks old. You may get a few non-spotted fish in the next generation if you get a male and female that are heterozygous, i.e., carrying the hidden normal gene.
High Fin refers only to an extended dorsal fin. If any of the other fins are extended, it is carrying the Lyretail gene. It is possible to have both. The genetics of High Fin are both simple and complex. The gene itself is a simple dominant; High Fin fry have to have at least one High Fin parent. However, the extent to which the fin is extended is controlled by a group of modifier genes, so you can get anything from a spiked dorsal to a broad fan. Basic selective breeding, using the best specimens, can improve the size and shape of the fin.
Chromedome wrote: Speckling on the swords is a dominant trait, as are all melanic mutations. They aren't likely to change much if your fish are more than a few weeks old.
Thanks. The reason that I was asking is that I have at least eight fry and they all show the same pattern of black spotting. Starting at mid-body from front to back, black spots appear and at some point the caudal turns completely black. About half show an abrupt change in coloration along a vertical mid-body line with the entire back half of the fish being solid black. I was just wondering whether this was the normal pattern that would change and "break apart" as the fish grew into spotted adults. (Patience is a virtue I obviously lack or I could have just waited to see what happens!)
Hmmm, I bought some green swordtails not too long ago as fry and they are just now starting to really show there spots. All of mine have spotting but nothing like you are referring too. It almost sounds like a tuxedo pattern you are describing. And to add one thing to chromedomes explanantion of the high fin gene it is also lethal in a double does meaning that any embryo with two sets of high fin genes will not develope; why exactly I still am not sure. Therefore all high fin fish carry one high fin gene and one normal fin gene. I have heard some people talk about producing all high fins from a mating of two high fins but I still have yet too see any actual documented proof.
Posted on: 2009/6/9 20:42
Michael Miller Fancy Xiphophorus Breeder "If you can not be good atleast be good at it." www.fancyswordtails.com
Joel, get us a picture! That is an unusual sounding pattern, which reminds me of the once-upon-a-time Jet Swords, except that they were red in front of the black. It could also be a combination of Tuxedo, as Mike suggested, with Wag pattern. I have some Red Tux Wags that have a much stronger black in the caudal than normal Tux types, very similar to what you describe.
Well, the black goes further forward than midbody. I can't be 100% sure, as they are still quite young, but I would say a very strong Tuxedo pattern, though there may be another melanic gene in there as well such as the Paint/Marble pattern. Such a combination often makes the black area darker and larger. I suspect that they may actually lighten up as they mature, they do appear to be pretty young.
Also, these fish are showing gold above the black area, and Green swords tend to be greenish grey or very pale beige there. It's likely that there is more here than currently meets the eye, some growth will be necessary to determine more than this. I would watch them closely, and even though it hurts, be patient!
Variatus and Swords are very closely related, but there are melanic strains of both fish. Joel's fish were labeled as Swords, and there is no reason to think they were mislabeled. Their appearance is consistent with a variety of Swordtail that is pretty well known.
Norton's book on genetics is a good place to start. There are a couple of other books, including Lambert's book on Platys and Swordtails. Might even help with figuring which green swordtail strain you may have, though if you got them at the ALA convention, I would have expected the location or strain to be written on the bag.