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Sunday, February 25, 2024


Have you ever wondered why Green-Blue-Purple Guppies suddenly occur in your dedicated breedings for a single color?  It’s all in the genotype…

Green Delta (pb/pb) and (Mgmg), expressing VEG modified to blue.

© Alan

© Alan S. Bias
Permission granted for nonprofit reproduction or duplication of photos and text with proper credit for learning purposes only.
February 25, 2024

International Fancy Guppy Association (IFGA) Green-Blue-Purple delta form a “continuum” of interrelated structural color expression.  Other than Y-linked orange peduncle ornaments, each lack sex-linked xantho-erythrophore (yellow-orange-red) color pigments in their body and finnage.

Structural color derives from a thin basal layer of violet-blue iridophores and melanophores residing in close proximity forming chromatophore units.  Actual expression is influenced several factors, including the ratio between violet and blue iridophores.  Further influenced by diversity in angles of crystalline platelets, which act as mirrors, residing under the violet-blue iridophore layer.  In conjunction producing variations in perceived color, i.e. green or blue-green or blue or blue-purple or purple depending upon angle of ambient light source.

(A) Heterozgyous Pbpb modified Dendritic melanophore-iridophore chromatophore units. (photo), and (B) Non-Purple Body (pbpb) Dendritic melanophore-iridophore chromatophore units.  (100X non-dissect, reflected lighting).

The primary genes at play include, but not limited to:  Purple Body (Pb), Metal Gold (Mg), and Vienna Emerald Green (VEG).  Each of which are conserved across multiple teleost species.

I.  Purple Body is a confirmed autosomal incompletely dominant gene that expresses in ratios of (1:2:1) in genotypes (pbpb : Pbpb : PbPb).  Which equates to (non-Purple Body : heterozygous Purple Body : homozygous Purple Body).  What this means is in perfect ratios, if all offspring survive to maturity, 1 out of 4 will be pbpb, 2 out of 4 will be heterozygous Pbpb, and 1 out of 4 will be homozygous PbPb.

Purple Delta (Pb/-) modified ornaments, expressing VEG, reduced xanthophores and increased violet-blue iridophores.

Pb has visible effect in heterozygous expression and amplified effect in homozygous expression. In heterozygous condition formation and migration of xanthophores which result in yellow color are inhibited. In homozygous condition formation and migration of xantho-erythrophores which result in yellow-orange-red color are inhibited.

Pb is often present in both Green and Blue.  Pb is always found in all-purple fish, but is not by itself sufficient to produce the all-purple phenotype in heterozygous Pbpb expression or homozygous PbPb expression.  While Violet is a true wavelength color, Purple is a composite produced by combining blue and red wavelength colors. Further removal of xantho-erythrophores, in conjunction with both increased populations and/or the visibility of modified melanophores and naturally occurring violet-blue iridophores, is required for production of the all-purple phenotype.

II. Metal Gold appears to be an autosomal incompletely dominant gene which would express in ratios of (1:2:1) in genotypes (mgmg : Mgmg : MgMg).  Which equates to (non-Metal Gold : heterozygous Metal Gold : homozygous Metal Gold).  What this means is in perfect ratios, if all offspring survive to maturity, 1 out of 4 will be mgmg, 2 out of 4 will be heterozygous Mgmg, and 1 out of 4 will be homozygous MgMg.

Mg has visible effect in heterozygous expression and amplified effect in homozygous expression. Though harder to quantify, in heterozygous condition formation and migration of xanthophores which result in yellow-gold color are often limited to specific regions of the body, such as the central caudal base, the dorsal and specific regions of the body.  In homozygous condition the entire body appears to be additionally covered by a yellow-gold cast.  As seen in Apple Green phenotypes.

IFGA Apple Green delta (MgMg), photo courtesy of Bryan Chin.

Mg is present in both Green and to a lesser degree in Blue. However, Mg is absent or masked in Purple. Mg expression is greatest in pbpb, i.e. non-Purple Body, reduced in Pbpb, i.e. heterozygous Purple Body and non-expressed or masked in PbPb, i.e. homozygous Purple Body.

III. Vienna Emerald Green is reportedly passed by Y-link mode of inheritance, though I have seen several instances of potential X-link in breeding tests.  VEG is most visible as a central green spot at the peduncle-caudal base, though should be considered a full body modifier that exerts influence body wide.

Vienna Emerald Green (VEG) Peduncle Spot.

VEG expression is greatest in pbpb, i.e. non-Purple Body, reduced in Pbpb, i.e. heterozygous Purple Body and non-expressed or masked in PbPb, i.e. homozygous Purple Body.  VEG expression is easily modified from green to blue.

Solid structural colored fish did not just occur in a single event or in rapid fashion to suggest they result from a single dominant gene.  Rather, the result was a long cumulative breeding process in which color pigment genes were removed and visible Variegation (Var) in the dorsal and trailing edge of caudals persisted for many generations.  Suggesting “solid” is an actual phenotype in which Var is still present and masked.  Being comprised of multiple small mutations in co-expression.

Such a hypothesis is supported by anecdotal evidence.  Primarily in the form of visible results from outcross breedings of Green-Blue-Purple to unrelated fish outside of this color spectrum.  Resulting F1 offspring always express Var to different degrees in body and finnage.  Further support is garnered by another simple observation that is indicative of the continued presence of Var in solid colored fish.  That being, solid colored Green-Blue-Purple fish always express a “black trailing edge” in the caudal and dorsal comprised of motile melanophores.  Which is suggestive of chromatophores needed to produce Var pattern being disrupted in co-expression and further repulsed to exterior edges of finnage.  Together, each supports solid colored Green-Blue-Purple fish being a true phenotype comprised of multiple gene expressions accrued over time.  

(A) Green Delta expressing Pb modified ornaments (Pb/pb) and (Mgmg). (B) Green Delta (pb/pb) and (Mgmg), photos courtesy of Bryan Chin. Note the deepening of the orange body spots.  Both males are expressing VEG.

(A) Blue Delta expressing Pb modified ornaments (Pb/pb) and (Mgmg). (B) Blue Delta (pb/pb), photos courtesy of Bryan Chin. Note the deepening of the orange body spot to pinkish-purple with Pb through xanthophore removal (arrows).  Both males are expressing VEG.

(A) Purple Delta (Pb/pb) males. Results of a homozygous Green (pb/pb) male x homozygous Purple (Pb/Pb) female breeding. (B) Homozygous Purple (Pb/Pb) male x homozygous Green (pb/pb) female breeding. This type male will express as either blue or purple depending upon the angle of light. Note partial modification of orange ornaments to pinkish-purple and increased violet iridophores (red circles).  Both males are expressing VEG.

In summary, zygosity dependent, the presence or absence, and concentration of Purple Body, xanthophores, and erythrophores is the primary distinction in spectrum between IFGA Green-Blue-Purple structural colored phenotypes.  


Bias A. S., Squire R. D., 2017 The cellular expression and genetics of an established polymorphism in Poecilia reticulata; “Purple Body (Pb)” is an autosomal dominant gene. Poec Res 7(1):1-32.

Bias A. S., Squire R. D., 2017 The phenotypic expression of Purple Body (Pb) in domestic guppy strains of Poecilia reticulata. Poec Res 7(1):125-146.


Things getting out of hand in your fishrrom?

 Re-define your goals and narrow your focus to obtain realistic results


Saturday, December 16, 2023



Why have Speartails dissappeared from the tanks of breeders in North America?  Think it's about time we make a change in that trend...

Multi-Colored Speartail, courtesy of Whitney, L 1952 - All About Guppies

© Alan S. Bias

Permission granted for nonprofit reproduction or duplication of photos and text with proper credit for learning purposes only.
December 16, 2023

For the past two years give or take I've started back working with Speartails.  Something I have not done since a teenager, and that was quite some time ago.  Over 45 years ago to be exact.  Foundation stocks for my current Speartail breedings were obtained from my good friend and fellow breeders Gary Lee of Taipei, Taiwan and Henrik Schneider of Großaltenstädten, Hessen, Germany.

Halfblack Snakeskin Speartail, photo courtesy Gary Lee
Over the last several years, starting with IKGH stocks, through outcross and consistent selection Gary has produced some wonderful results within his Speartail breeding program.  While working with varied genotypes, to date, he has concentrated primarily on showing Halfblack Snakeskin (NiII, SSb/t) phenotypes.  Periodically entering his best fish in IKGH shows and providing his stocks to breeders not only in many parts of Asia, but also Europe and North America.  His breedings and show results can be found and followed at The Guppy Master Project.

Schimmelpennig Platinum Speartail, photo courtesy Henrik Schneider

Henrik has also produced some wonderful results within his Speartail breeding program.  He has concentrated primarily on Schimmelpennig Platinum (Y-Sc) in Blond (b) & Purple Body (Pb) phenotypes.  Also entering his best fish in IKGH shows and providing stocks to breeders in Europe, and now Asia and North America.  His breedings and show results can be found and followed at Hessen Guppys.

At one time Speartails, and other small tail phenotypes, were quite common in North America and around the world.  Reasons for loss of interest and thier demise can only be based on speculation.  In part the rise of Broadtail phenotypes, to include delta and viel, in the 1950-70s played a played a roll in declining interest.

Photo courtesy Madsen 1974 - Aquarium Fishes in Color 
I suspect an often lessor considered culprit came to play for many breeders.  That being a rather complex genotype.  Color and pattern aside, Speartail body and finnage is derived from several combinations of X-link and autosomal genes that are needed to produce desired results in both heterozygous and homozygous conditions.  The latter producing long and thin elongations of the gonopodium referred to as "spirelli" in breeder circles. Resulting in a high cull rate.

Such extensions preclude use of many of the best Speartail males as potential sires without surgical alteration or at best use during a very brief period of time just after the onset of sexual maturity.  Well before mature finnage and other attributes can be thoroughly evaluated.

Speartail is also intrinsic with Opaque (Op) genotype.  Another autosomal incompletely dominant gene which alters angles of crystalline plateletes which reside under the violet-blue iridophore structureal color layer.  Producing "dull and muted" colors, i.e. translucent scale phenotypes.  In homozygous fashion this color inhibition can be quite dramatic, again resulting in a high cull rate.

Lacking a class to exhibit within the International Fancy Guppy Association (IFGA), Speartails are now rarely seen, if not absent, in the tanks of American and Canadian breeders.  Though, they have persisted in the hands of Europian breeders and within the confines of International Kuratorium Guppy High-breeding (IKGH) shows.

In Asia interest in breeding Speartails has seen a steady increase over the last several years.  Though, much of this interest has been commercially driven and not often in the hands of breeders dedicated to producing show quality stocks that adhere to established IKGH standards.  While resulting in many novel Speartail phenotypes, quality is often lacking and many fail to take hold and persist in breeder tanks.

On occasion, "spear-like" phenotypes are seen among breeder results with wild-type Guppies.  Most of these do not stem from defined Speartail breedings.  Rather, they derive from reciprocal Peocilia reticulata x P. r. wingei breedings.  While such individuals can be refined through selection and backcross into true Speartails, most are used in a fashion which continues to produce haphazard results. 

As with all complex phenotypes, selection for Speartails cannot be maintained indefinitaely without periodic outcross from compatible stocks existing within a breeders population or from infusion of unrelated stocks sourced from other breeders.  Attempting to linebred long-term or indiscriminately will result in severely reduced fecundity across all aspects, both visible and unseen.

Speartails, like many unique finnage modifications, require a rigid selection criteria requiring high rate of culling to produce a rather small percentage of desired result.  Upon outcross, initial F1 and F2 offspring will produce a varied result in dorsal and caudal expressions.  Most of which will be culled from a breeding program.  A select few may be used to recombine desired genotype.  

F1 Lowersword x Spear outcross

At the moment I'm working with two specific phenotypes and outcrossings with my various Lowersword phenotypes, as seen in the following photos.  Will see where this journey takes me and if they will continue to hold my long-term interests?  Only time will tell...

Blond Schim Plat Purple Body Spear

Blond Schim Plat Purple Body Spear

F1 Lowersword x Blond Schim Plat Purple Body Spear

F1 Lowersword x Blond Schim Plat Purple Body Spear

Red Snakeskin Saddleback Spear

Red Snakeskin Saddleback Spear

Red Snakeskin Saddleback Spear

Red Snakeskin Saddleback Spear


Find you're spending less time in your fishroom?  Maybe it's time to refocus and reaffirm your goals and interests in breeding.  Show season is just around the corner!


Thursday, March 16, 2023


Working With Vienna Emerald Swords

Do Breeders excessively concentrate their efforts on production of singular phenotypes at the expense of overall genotype?

Grey Vienna Emerald Doublesword male

© Alan S. Bias
Permission granted for nonprofit reproduction or duplication of photos and text with proper credit for learning purposes only.
March 16, 2023

When it comes to breeding Vienna Emerald Swords, I find the biggest issues are often created by the breeders themselves.  Most breeders try to maintain complex strains with far too few breeding’s in too small of a population.   Especially, when compatible breeding schemes are not utilized across multiple phenotypes comprised of similar genotypes.  Such as Blue – Green – Purple in solid or halfblack.  Compatible breeding schemes allow for creation of a much larger “combined breeding population” within an individual fish room or shared among breeders who regularly exchange their stocks.

Several breeding’s made yearly and maintained in a dozen tanks is a requiem for failure when maintaining complex phenotypes in isolation. In my experience a minimum of 40-60 tanks are required to maintain a strain long-term.  Keeping in mind, a breeding strain is not necessarily comprised of a single phenotype.  Rather many phenotypes as a collective group.   At times I run 80-100 tanks of Lowerswords, saving 50-100 drops per year.  A large population allows for needed beneficial mutations to accrue through various genetic principles and mechanisms.  This same concept also allows for identification and culling of deleterious alleles, without need for drastically reducing numbers at any given point in time.

Grey Vienna Emerald Lowersword male

Far too many breeders are focused on linear breeding’s and routinely turning a generation with each breeding result. When your fish are at a point that is satisfactory to you as a breeder it is OK to maintain a "status quo" and utilize the same generation via lateral breeding’s for 2-3 years. Backcrosses can further alleviate the perceived need to turn a generation to improve results.

Think of your breeding program in terms of an isolated wild-type or feral population.  Poecilia reticulata (Guppies) are not like seasonal breeding Salmonid populations.  Healthy Guppy populations are maintained through multiple breeding's throughout the year, and comprised of multiple age groups at any given time.  Why should we as breeders not maintain our domestic breeding programs along a similar parallel as found in healthy wild-type?  I have done so for decades.

In addition to multiple sex-links both X and Y, sum total genotype of "Vienna Emeralds" includes multiple autosomal genes. Both recessive and incompletely dominant.  Autosomal variation, the random nature of recombination among autosomal genes, precludes production of a single "fixed phenotype" in high numbers for extended periods of time.

Mother Nature imposes this principle for a reason.  That being, autosomal genes confer positive benefit only in heterozygous fashion. Attempting to maintain autosomal genes in homozygous fashion long-term confers negative benefit across multiple areas of fecundity within and beyond color-pattern, size and shape. An easy example to visualize is Sickle Cell Disease. The sickle cell anemia gene confers positive benefit to individuals and populations in heterozygous fashion, i.e., immunity from malaria. Yet, in homozygous fashion is lethal.

Grey Purple Body Lowersword male

Another example in Guppies is autosomal incompletely dominant Purple Body (Pb).  Pb mode of inheritance allows for populations to be comprised of three phenotypes:  pbpb - Pbpb - PbPb in a 1:2:1 ratio.  Each construes positive or negative benefit in open or closed canopy environments under a multitude of predation regimes.  In breeder tanks each is used as a "tool" for propagation and maintenance of specific phenotypes.  When Pb selection is narrowed wild-type, feral and domestic populations suffer in the long-term.

Grey Vienna Emerald Doublesword males

These same principles apply to all autosomal genes, if you know where to look. What does this mean as a breeder of autosomal genes?  Rather than seeking to narrow your genotype in quest of a singular phenotype, focus your breeding program on maintenance of multiple autosomal genes, in various states of zygosity, to produce a multitude of phenotypes within your overall breeding scheme.  

In turn, this will strengthen your breeding population as a whole.  Yet, allow for production of a smaller percentage of desired results across multiple phenotypes…

Grey Vienna Emerald Lowersword male


The number of tanks you maintain as a breeder is not the point.  Because it will never be enough.  The point is whether you utilize your available tanks efficiently in quest of your desired result.  Set your goals realistically...


Wednesday, April 29, 2020

Skilled Vision Among Breeders

Historically, the best Pedigree Breeders always have and always will breed by eye. They are visual thinkers.  Such breeders are often very instinctive and gifted with “Skilled Vision.”

Golden Bunt Lowersword

© Alan S. Bias
Permission granted for nonprofit reproduction or duplication of photos and text with proper credit for learning purposes only.
April 29, 2020

Skilled Vision has been loosely defined as a learned practice that allows for recognition and productive results.  Based on powers of observation and acquired knowledge, with far less proficiency in the language of science. 

Successful breeders possess skilled vision to varying degrees, and are able to develop a needed understanding of selection from hands on experience.  Good practice results from recursive breedings made over time followed by evaluation of results.  Incorporating skilled vision and practice in attempt to control selection of genotype, while allowing for positive traits with reproducible results in future generations.  This is the nature of Domestic Pedigree breeding.

Skilled vision can be viewed as a discipline involving multiple sensory inputs.  It has a genetic basis, and is not simply the result of accrued knowledge &/or environmental conditioning (formal education & training).  Yet, skilled vision can be enhanced through breeder communications, exchange of ideas, formal competitions, farm visits, breed standards and scientific knowledge. 

Purple Body (Pb) Lowersword female
Taken as a whole, skilled vision allows a breeder to process and make sense of what is seen day to day.  Breeders often lack expansive terminology to express their accrued knowledge to others.  Rather than relying on anecdotal terminology, the language of science can allow for conciseness in conversation.

Is there a dichotomy between the art of breeding and science?  Yes. While science can help a breeder understand results and clearly communicate them to others, extensive reliance on science in breedings can result in a loss of “balance” in results.  This has been seen in many commercial breeds over the last several decades.

Is there dichotomy between a successful breeder and his lessor peers?  Yes.  Those with skilled vision can take breedings to optimum levels of achievement and maintain them long-term. 

Various Lowersword "Bunt" phenotypes.
Science allows me, as a breeder, to maintain a vast array of phenotypes, with truly little effort, in a related breeding program through understanding of the sum total genotype.  Knowledge of chromatophore interactions that determine color & pattern; what is possible and what is not.

While maintaining a reference collection of nearly 5,000 scientific research papers, this falls short of the visual aids I routinely rely on.  In the form or nearly 70,000 photos of guppies from personal breedings and that of others.   To this you can add another 25,000 microscopy images made over the last 10 years.

My breeding notes are embarrassingly minimal and rarely referenced in day to day practice.  Since childhood, sensory perception and visual analysis of the surrounding environment has always been my preference.  Visual images often convey far more meaning than printed words.  As a result, find little need to convert images to words in my mind.

Observation allows for a balance in results within my breeding program…

Grasseni, Cristina. "Skilled vision. An apprenticeship in breeding aesthetics." Social Anthropology 12.1 (2004): 41-55.

Grasseni, Cristina. "Designer cows: The practice of cattle breeding between skill and standardization." Society & animals 13.1 (2005): 33-50.

Grasseni, Cristina, ed. Skilled visions: Between apprenticeship and standards. Vol. 6. Berghahn Books, 2007.

Grasseni, Cristina. Developing skill, developing vision: practices of locality at the foot of the Alps. Vol. 3. Berghahn Books, 2009.

Tuesday, October 16, 2018

35 Years of Breeding Blond Lowerswords

Download link for complete publication:  English and Mandarin text.

Early Bias Blond (bb) Purple Body (PbPb) Translucent Scale (undescribed)
Lowersword (Y-Ls) circa 1985.

Current Bias Blond (bb) Lowersword (Y-Ls) 2018.

Download link for complete publication:  English and Mandarin text.

Click on blog photos to enlarge

Click on blog photos to enlarge