Longfin Confusion

Longfin Confusion

For years I have watched people offer standard fin bristlenose for sale to people, stating that these fish carried a gene for longfin. I felt very bad for the people wasting their money and worse wasting the next year or two raising and breeding these standard bristlenose just to findout that all of the babies would look just like mom and dad. As recently as last week we received a call from a customer wanting to place an order for some standard fin, or “normal” super-red bristlenose that carry the longfin gene. It is an understandable mistake to think that the gene that is responsible for the longfin trait might be recessive, but this misunderstanding has been going on far too long now.

We are primarily known for our work with angelfish since we have worked with the longfins or veiltails in angels since the 1970’s. It is well known, and has been for years, that the gene responsible for veiltail in angelfish is dominant. In other words, if the fish carries a gene for longfin, it will be a longfin.  An article written in 1982 for FAMA magazine by. Joanne Norton described the veiltail gene as follows: Veiltail in angelfish is due to an autosomal (not on a sex chromosome) dominant gene (Sterba). A double dose of the gene for veiltail results in a very long, droopy tail. The double-dose veiltail is smaller and less vigorous than the single-dose veiltail and is not a prolific breeder. A mating in which both parents are single-dose veiltail is unsatisfactory because this produces 25% normal, 50% single-dose veiltail, and 25% double-dose veiltail. You need to sort three kinds of fish and also the double-dose veiltails are slow-growing and not as attractive as the single-dose veiltails. It is better to obtain veiltails from a cross of a single-dose veiltail x normal, which will produce 50% single-dose veiltail and 50% normal offspring.  Well, in our experience the same can be said for Longfin in bristlenose.

If you have bothered to read this far, and if you are anything like me, you are probably thinking, “Guess what Dave, this isn’t an angelfish. It’s an ancistrus. It’s a different specie. It probably has a different number of chromosomes. The genes may work differently”. I can only say that every cross that we have done breeding longfin and standard fin bristlenose (in the hundreds) has shown us that it does work the same as it does with angelfish. If your bristlenose carries the gene for longfin, you will see it!

Comments are welcome as always.



  1. Hi Dave;

    Are there modifier genes that enhance the long fin effect? That’s one gorgeous looking ABN.


    • Thanks Willie. Great to hear from you. Your question is a really good one, probably worthy of a nice long article. I wish I could answer it with a simple “yes”. It would be so much easier. lol. I’m sure you know how much we as breeders have to rely on observation. I’m pretty sure you are correct and there are modifiers involved. If we only had a nice lab and a bunch of grad students we might actually be able to prove it. I will try to explain some of it for other readers and if Mark Zuckerburg happens to be reading this he may want us to have the latest in genetic research equipment.

      It appears that there is a gene that controls the expression of the long fins.  This gene expresses dominance over the normal “wild type” version which has short fins.  Another example of fish, and there are many species, that consistently produce long finned variations, is the angelfish. 

      Modifier genes influence the expression of other genes.  In the case of angelfish, we have very large spawns to observe.  Some fry will have a wide caudal (tail) while others may be slightly more narrow caudal or have attractive extensions off the trailing edge.  These slight differences are the work of modifiers for the gene that expresses the long fin trait. 
      Our long finned bristlenose show many of these same characteristics that appear in angels. Part of the problem with answering the question of modifiers is that in order to create a longfin bristlenose, some breeders may have had to cross species. Each specie is slightly different. When we look at a spawn of 50 long finned bristlenose and we see slight differences in these long flowing fins, are we seeing different specie genetics or are we seeing modifier genes at work? Example: Ancistrus cirrhosus is probably the most commonly collected bristlenose sold in the industry. Most albino bristle nose should belong to this specie. Years ago we acquired a pair of albino bristlenose that produced brown fry. The gene for albino must have been in different locations on the chromosomes of each parent. Was this albino pair the result of an earlier specie cross? We don’t know. Another example is the Super red bristlenose. Was it created using L144, common name (blue eyed) or (black eyed yellow)? Did it result from a cross to wild type? They will breed with each successfully. We have done those crosses. American fish breeders receive much of our stock from Europe and the Orient. We really don’t know exactly what we are dealing with in terms of their genetic make up.

      I do currently have a nice group of 40 young adult longfin bristlenose growing out in a 55. It’s interesting to note that although some of these fish are red longfins and some are blue eyed longfins, they all have very similar fin length and shape. Of course these are our lines. There are lots of other breeders working with them so we may see some lines that show different characteristics when we get a chance to compare them. There are a number of companies currently do gene maping, and the prices are starting to come down. I have a feeling we will be able to get the answers to some of our questions in the very near future. It is possible that some of the larger tropical fish clubs with financial resources are doing it already. Comment

      • Willie, let me add to what Dave wrote. There is another factor that will likely cause fin shapes to differ and that is whether the gene for Longfin is heterozygous or homozygous in a particular fish. If it acts anything like angelfish, then fish that are homozygous will have longer, weaker finnage. Combine this with the factors of differing species, modifier genes (especially if they are polygenetic), and I don’t think we’ll know the answer anytime soon – at least not in our lifetimes. 😉

  2. I’ve done the same experiment over 7 generations, one of the smaller scale programs I worked on and I came out with the same conclusion.

    If the longfin gene is present it will show.

  3. One of the folks in my club (MAAH) is currently doing just that same experiment , because he was questioning the validity of the long fin gene carrier. I found it ironic that I just fell across this blog a week after he started setting up his tanks to experiment.

  4. This man knows his stuff. Good article and simple to read.
    Keep up the good work.
    You are looking good boy!

    • Thanks Miguel. Always good to hear from you.

  5. Well explain. These days I’m more of a discus guy. but Angels are still one of my favorites. I usually buy supplies from you Dave.
    But When I come back from this deployment I will hit you with bristle nose pair.


  6. I always enjoy your blogs. Thanks for taking the time to write them, Dave!

    • Thanks Jake. It’s great to know that someone out there is reading them lol.


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