PART I: What are Cypriniforms and why does anyone care?

Minnows, carps, loaches, and their relatives – known as Cypriniforms – are an exceptionally diverse group of fishes (4,182 currently valid species according to the Catalog of Fishes) that come in a wide range of sizes, shapes, and colors . Their overall small size and aesthetic variation has made them appealing to the aquarists (does the clown loach [Chromobotia macracanthus] look familiar?)! In fact, aquarists are some of the most knowledgeable people on these species!

Just as interesting is that Cypriniforms can be found across multiple continents in a variety of habitats with unique foraging, locomotive, and reproductive patterns and morphologies and fill a variety of ecological roles (e.g., predatory and prey). For example, the fathead minnow, known scientifically as Pimephales promelas (Check out this blog post by Liz Marchio for an excellent explanation of scientific names!) develops excessively large tubercles on a really dark, swollen head during the breeding season (see some images here). There are THOUSANDS of other interesting species. Just hit up Google and start searching!

As an evolutionary biologist, I am interested in understanding and conserving patterns of phenotypic diversity and novelty: How did what’s here get here and how can we keep it here? I think the best approach is to look at what we know about Cypriniform diversity and what we know about the evolution of that diversity, first. That is, how are those 4,182 species distributed across groups and how are those groups related to each other. Accordingly, I am splitting “my first blog post” into a three-part series. Part I will provide insight into what a Cypriniform is and the distribution of species across families. Part II will focus more on each family and what makes a Cobitid a Cobitid and a Cyprinid a Cyprinid. Part III will then focus on the evolutionary history of this group, how the families are related to each other, and what the implications are for the evolution of Cypriniform diversity! After that, my goal is really to blog about anything I find interesting for minnows – recent research using a particular minnow species, a pretty new species I saw at a pet shop, an update on the taxonomy of a particular group. Really, pretty much anything Cypriniformish.

First, what is a Cypriniform? I’m sure you think this should be an easy question to answer, right? It’s a small fish that goes in my aquarium…or that I see at the edge of the lake…or…OK, not really. It is actually difficult to answer this question in a way that makes most people go “aha, I understand!” Given this problem, let’s stick with defining a Cypriniform as any fish with a kinethmoid. What?!?!? OK, the kinethmoid is a tiny bone used in jaw protrusion (e.g., eating) and is found only in species that are considered Cypriniforms. Makes sense, right? What does it look like? Check out this photograph:

(Photo: Gerhard Ott,

Photo: Gerhard Ott,

This photograph is a dorsal  view – standing over the fish and looking down on its mouth – of the the jaw bones from a cleared-and-stained specimen of Homaloptera ripleyi (from Ott 2009). The five bones labelled are the maxillary (Mx), premaxillary (Pmx), anterior process of prexmaxillary (anP), ascending process of the premaxillary (asP), and the, wait for it…kinethmoid (Ke)! It may take some Googling and a brief review of your anatomy to identify each of these bones and understand the kinethmoid, but now you know the kinethmoid is a legitimate bone in Cypriniforms (read more in Staab et al. 2012). For the future purpose of this blog, we will assume that any species classified as a Cypriniform is appropriately classified and has a…kinethmoid!

Now, let’s look at the distribution of that diversity, taxonomically speaking. Although still debated and it may change, there are currently 11 recognized families of Cypriniforms according to the Catalog of Fishes (listed in no particular order):

  • Cyprinidae (2960 species)
  • Psilorhychidae (24 species)
  • Cobitidae (245 species)
  • Balitoridae (230 species)
  • Nemacheilidae (627 species)
  • Serpenticobitidae (3 species)
  • Vaillantellidae (3 species)
  • Ellopostomatidae (2 species)
  • Barbuccidae (2 species)
  • Gryinocheilidae (3 species)
  • Catostomidae (83 species)

There are a few quick observations that we can make here:

  1. The family Cyprinidae is exceptionally diverse relative to all other families of Cypriniformes. This family is an order of magnitude larger than the diversity in all other families. The next most diverse family contains only 627 species (Nemacheilidae), only 15% of the diversity observed in Cyprinidae!
  2. The disparity of taxonomic diversity is unusual. There is one exceptionally diverse family (Cyprinidae), four families with moderate diversity (Cobitiidae, Balitoridae, Nemacheilidae, Catostomidae), and six families with low diversity (Psilorhynchidae, Serpenticobitidae, Vaillantellidae, Ellopostomatidae, Barbuccidae, Gyrinocheilidae). It’s an unusual pattern worth exploring more.

What do you think? Are there any patterns about the distribution of diversity in this order that you notice? Next time, I will focus on what species in each of these families look like and provide some information about each of these groups!



Ott, G. 2009. Redescription of Homaloptera ripleyi (Fowler, 1940) from Sumatra, Indonesia (Teleostei: Balitoridae). Bulletin of Fish Biology 11(1/2):73-86.

Staab, K. L. 2012. Comparative kinematics of cypriniform premaxillary protrusion. Zoology 115(2):65-77.


About James C. Cureton II

I am a PhD candidate at the University of Oklahoma interested in the ecology and evolution of fishes, most notably Cypriniformes! Check out my personal website ( or follow me on Twitter (@Cureton2J) to stay up-to-date with the blog and other information! I am interested in teaching others about this diverse group of fishes and learning about them from others who are more informed! I started this blog to synthesize common and scientific knowledge of this group in a way that will reveal just how spectacular this group of fishes is! I am also interested in learning from others so if you have some useful information, please share it in the comments section!
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9 Responses to PART I: What are Cypriniforms and why does anyone care?

  1. Hello James,

    I’m Gerhard from Germany, especially studying Cobitoidea (one of the suborders of the order Cypriniformes). I guess Your list can be illustrated like in a picture I made for Cobitoidea
    (download here:
    If You need a osteological photography of a kinethmoid of a loach (Homalopterula ripleyi): I have one.

    I will visti Your blog again!


    • Thanks for visiting my blog, Gerhard! I would love to use your Cobitoidea picture on the blog if you are OK with that? Also, if you would be willing to send me a picture of a kinethmoid, I will definitely post that on the blog (I would certainly appreciate it as I am sure readers will too!). I would obviously give you photo-credit for both pictures. Thanks for visiting my blog and offering of your images!

      • Hello James,

        I uploaded for You a picture and a publication-pdf. The abbreviations in the picture You will find explained at p. 84, fig 10. of the paper (Ott, G. (2009): Redescription of Homaloptera ripleyi (Fowler, 1940) from Sumatra, Indonesia (Teleostei: Balitoridae). – Bulletin of Fish Biology 11 (1/2), 73–86.).

        Note the loach is know in genus Homalopterula (formerly a subgenus of Homaloptera). The loach-tree is a first picture of lecture of mine (and I made an english version). You’ll find the material – including a photo of a living specimen – packed for download here:

        Please credit like this “Photo: Gerhard Ott,” if possible.

        Good luck for Your website and projects!

      • Thanks! I appreciate allowing me to use your photographs and will give you the appropriate credit!

  2. Pingback: Part II: What are Cypriniformes and why does anyone care? | Cypriniformes Anonymous!

  3. Pingback: Part III: What are Cypriniformes and why does anyone care? | Cypriniformes Anonymous!

  4. Yabby says:

    A blog dedicated to such an interesting group of fishes is a wonderful thing. It’s a bit off topic but I find tubercles or “pearl organs” to be fascinating. The small round ones of Pimphales promelas are cool, but then you get something like Rutilus virgo (or Rutilus pigus subspecies maybe?) and it just looks crazy, the males become living mucus coated maces. I would hate to think, they would try to stimulate females to spawn like other cyprinids, with those thorns. It’s probably for fighting other males and possibly courting (visually). But who knows 🙂

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