Swordtail Guppies, a brief discussion

Some history and a little personal experience over the last 40 years breeding them.

Grey Bunt Zebrinus Lowersword (Y-Ls)

Grey Bunt Zebrinus Lowersword (Y-Ls)

© Alan S. Bias

Permission granted for nonprofit reproduction or duplication of photos and text with proper credit for learning purposes only.  August 31, 2024 

I’ve been keeping and breeding Guppies since I was eight years old ca. 1969.  Prior to this my father kept a few tanks of near wild-type.  Including a tank in front of my high chair as an infant.  Around 1982 my involvement with the International Fancy Guppy Association (IGFA), along with the breeding and showing of pedigree Guppies began. 

After several years of dabbling around with various Delta strains in 90 tanks, I became intrigued with the world of Swordtail Guppies after finding most Deltas just too large, short lived and sluggish at maturity.  More importantly, Delta demonstrated a general lack of anterior-posterior autosomal color-pattern which had been selected against in a quest for the long sought after solid-colored Guppy.

I formed a long-lasting friendship with the late Don Sauers, a breeder who dedicated most of his years in the hobby to promoting and showing the Swordtail Guppy.  Don did not maintain a large fishroom in his home at the time.  Guess he saw enough fish working in the pet industry.   Around 40 tanks in total, if memory serves.  Of which, one was a large 80+ gallon homemade plywood tank painted blue with a glass front.  In which me kept various African Cichlids.  Several of the breeding tanks were devoted to his limited interest in Deltas, while the majority housed his beloved Doublewords (Ds), Lowerswords (Ls), and a few Topswords (Ts). 

On my first visit to his home in the early-mid 1980s in Columbus, Ohio he pointed out the fish he wished to keep and handed me a net.  For the next several years, in conjunction with Fred Roll and several others, we would show fish against each other one week, and swap stock the next.  Swordtail Guppies have captivated me ever since with their variety, longevity and hardiness.

In the late 1980's and early 1990’s it became apparent to some of us breeders the rigid restrictions imposed upon Swordtail breeders by International Fancy Guppy Association (IFGA) & International Kuratorium Guppy High-breeding (IKGH) well defined show standards, as interpreted by essentially Delta judges, for clear caudal, thin tapering dorsal, narrow caudal shape, strict body-caudal ratios, and reduced color were not only outdated, but severely limited potential for the development of new and novel Swordtail phenotypes.

Bias Ls ca. 1988

Swordtail standards around the world were, and still are for the most part, based on a 1960-70's understanding of genetics and a desire to foster solid colored fish.  In the end it limited our understanding of alleles & gene complexes needed to create Swordtails with a free hand as artistic breeders.  By doing so, it curtailed improvement in Swordtail color, pattern & shape not only in North America and Europe, but also around the world. 

At some point, I decided I am not a “show breeder”, but a “pedigree livestock breeder”.  As a result, I should state that I do not, have not and will never breed my Swordtails Guppies strictly in accordance with any fixed set of show standards.   I do not seek to create a breeding show strain within these narrow confines.  Rather a sound pedigree domestic strain which is reproducible over multiple generations.  One that I can in turn regularly show.

My breeding practice is very straight forward and simple.  I keep few records or notes, and rarely refer to them.  Bear in mind, this applies only to my pedigree breedings and not any planned research breedings for later publication.  I am a sight-breeder who practices skilled vision.  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.  I study genetics not always to make decisions, but to learn how to avoid reinventing the wheel with every generation.

Current Fishroom

I allow the genotype(s) within my breeding population to lead me in pursuit of the best genetic result for all aspects of fecundity, including color-pattern, by imposing sound breeder selection criteria common to all forms of pedigree livestock breeding.  Stated another way, I breed my fish as I once did my pedigree cattle and pedigree sheep, without ever losing sight of wild-type Poecilia reticulata body, shape and form.  During this process I select for upper moderate body size and maximum sustainable caudal-dorsal extension in several forms at maturity.  All the while maintaining longevity and fertility.  I simply show those individuals at maturity, and not before, that fit accordingly into various shows around the world.  Which most do with rigid culling and selection practice.

All Guppies, including Swordtails, are comprised of sex-linked xantho-erythrophore color pigment (if present), over a layer of violet-blue iridophore structural color, on top of a layer of basal level melanophores.   Under which reside crystalline platelets, acting as mirrors, which determine reflective qualities based on stacking (parallel vs. diverse angles).

Variegation (Var) is comprised of collections of large linear and circular dendritic melanophore in close proximity to violet-blue iridophores, forming dense structures in body and finnage.  Var may be static or motile in nature, i.e. mood dependent expression.  Var is part of wild-type counter-gradient camouflage, in ectopic fashion (residing in upper dermal layers).  Known in breeder circles as “Eye-Spots”, they are generally masked by “solid-genotype” found Deltas.  Outcross will disrupt masking to reveal Var in F1 offspring.

All Swordtails, selected for highly reflective qualities, express Variegation (Var), including Eye Spots to varying degrees.  Highly reflective Swordtails, in contrast to many or most Delta and several small tail phenotypes, to include Roundtail & Speartail, are selected against Opaque (Op), i.e. translucent scale.  Op, zygosity dependent, results in muted and dull coloration, in both males and females, by producing diverse angles in crystalline platelets.  OP is an integral part of wild-type counter-gradient camouflage.

In earlier times, ca. 1970-90, few outcrosses were made by Swordtail breeders with existing Delta strains, other than neutral IFGA Green Delta females.  Such breedings did not result in long-term improvement to Swordtail breeding lines.  This, a direct result of outcrossing with homogeneous solid-colored Deltas largely limited to sex-link structural violet-blue iridophore coloration.   In doing so, all or nearly all autosomal color-pattern could be lost in the short-term.   Including reflective qualities.

These breedings simply produced large dead-end hybrids destined for the show bench, which are genetic dead-ends in a pedigree breeding program.  This occurred only after several generations of backcross to parental Sword strains to regain sword shape and extension.  Any perceived positive results in larger size also resulted in corresponding negative results for reduced reflective qualities, loss of sex-link color, and most importantly autosomal color-pattern.  Which constitutes the basis for highly reflective qualities found in Vienna Emerald Green (VEG) Swordtails.

Over the years, I have relied on rigid selection criteria from within my large breeding population to identify and expose unexpressed color-pattern, and limited outcross to near wild-type for infusion of new traits not found in my existing breeding population.  Rather than outcross to Delta strains, followed by backcrossing to parental Sword strains.

As a rule, I find Swordtail genotypes to be rather straight forward in mode of inheritance(s) for swords and specific sex-linked color-pattern.  Co-expressions and crossover events will often mislead the novice breeder into misinterpreting results.  What is often hard for many breeders to comprehend is the concept of sword type, shape, color and extension not always resulting from singular sex-link genes.  Often, they are result of unbreakable linked gene complexes.   Specific composition can result in better or worse shape and coloration via attraction or repulsion of chromatophores.  Such as yellow, comprised of sex-linked xanthophores residing over white leucophores &/or static autosomal Metal Gold (MG) will produce better result than red, comprised of sex-link erythrophores.  While blond (b) with reduced size and numbers of melanophores found in Var produces better shape than grey.  Refinement tends to come from linebred females, and to a lesser degree males, via positive autosomal concentration.  Whereas detrimental result in shape, color and extension tends to arise from negative disruption via outcross.

Swordtail modes of inheritance can generally be described as follows:

Lowersword (Ls) mode of inheritance is traditionally Y-linked for swords and much basic color-pattern, with a neutral "X" for caudal shape and additional male sex-limited color-pattern expression.  Periodic crossover to X-Ls is common.  Resulting in Lowerswords comprised of Y-Ls, X-Ls and even XY-Ls in co-expression.  I should note that stand-alone X-Ls rarely produce show quality results.

Lowersword (Y-Ls / X-Ls)

Lowersword (Y-Ls)

Topsword (Ts) traditionally fall into two modes of inheritance.  Those expressing Snakeskin Body and Tail (SSb/t) are found in a linked complex of X-Ts, SSb/t.  Those lacking SSb/t are generally Y-linked.  Though, crossover is periodically seen.

Topsword (X-Ts, SSb/t)

Topsword (X-Ts)

Topsword (Y-Ts)

Doubleswords (Ds) mode of inheritance is more complex.  Those expressing Snakeskin Body and Tail (SSb/t) are found in a linked complex of X-Ts, SSb/t.  Those lacking SSb/t are generally X- or Y-linked Vienna or Multi type with periodic crossover.  As such, many are a co-expression of XY-Ds.  Ds are often found in co-expression with X-Ls or Y-Ls  or X-Ts or Y-Ts.  In such true multi-gene Ds phenotypes at various stages of growth mismatched shape, size and extension are common between the upper and lower ray extensions.

Doublesword (Y-O / X-Ds)

Doublesword (Y-Ls / X-Ds)

There are several known linked complexes for Ds and color that pass as a single mode of inheritance.  To include:  Asian X-red, Ds and Asian X-yel, Ds.  Both of which can be combined in co-expression with Y-Ls, or Y-Ds, or Y-Ts.  Though, best results are often achieved with neutral Y-O males used as sires.

Doublesword (Y-Ls / Asian X-red, Ds)

Doublesword (Y-Ls / Asian X-yel, Ds)

Some Ds are simply true phenotypes.  Being solely comprised of Ls and Ts in co-expression, i.e. they are a  non-genetic Ds expression.

Doublesword (Y-Ls / X-Ts)

Differences in expressions between X- &/or Y-link Ls, Ds, Ts produced by crossover events results in peculiarities that breeders can sometimes recognize with experience and enough breedings.  However, most examples of crossover in Ls, Ds, Ts often go unseen by breeders unless regular reciprocal breedings or outcrossing’s are made.

Unfortunately, show standards and the decisions of the powers to be are not always conducive to the best results in pedigree Swordtail breeding.  How a breeder decides to select for traits is a personal decision that should be based on long-term goals, sound practice and ethical considerations for breed attributes.  Breed attributes in this case, should adhere to wild-type Poecilia reticulata body, shape and form.  Otherwise, you run the risk of compromising structural fecundity.

For a pedigree breeding program to succeed long-term your goals should be generally established well before you make the first breeding.  Otherwise, you run the risk of wandering aimlessly.  During which time your breeding population may crash from lack of direction.  Yet, at times you may find need to deviate on occasion to circumvent unforeseen results.  That is part of being a pedigree breeder.  Always make as many breedings as possible and maintain as large a potential breeding population as possible.  In this manner you can make benefit of Mother Nature’s gift to pedigree breeders.  That being the frequent mutations via segregation and recombination during meiosis that occur each generation.  At all times, if and when deleterious alleles are revealed select against them severely to purge from the breeding population.  Do not routinely rely on outcrossing to mask them…

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Long-term selection and attention to detail can reward a breeder not only with positive results, but novel phenotypes not yet introduced into Pedigree Guppy breedings.  Share them with friends as they can just as quickly disappear...

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LONGEVITY AND FERTILITY OF LOWERSWORD MALES

Both longevity and fertility can be linked to genetic and environmental inputs.  Can negative result be alleviated with positive selection practices?

First of two surviving 40+ month old Blond Bunt Ls breeder males.

 

Second of two surviving 40+ month old Blond Bunt Ls breeder males.

© Alan S. Bias

Permission granted for nonprofit reproduction or duplication of photos and text with proper credit for learning purposes only.  August 13, 2024 

Several years ago I decided to test the current longevity and fertility of males in my Lowersword strain.  Something I had not done for some time.  I kept a group of 4 sibling Blond Bunt Ls males until demise in an active breeding group. Periodically replacing all females with new virgin females to keep aged males active. All males lived well over 40 months and were fertile until demise. The last two met thier fate this past Spring within days of each other.

Last surviving 40+ month old Blond Bunt Ls breeder male.

I should state from the outset, that I am a pedigree breeder of livestock. Not a breeder of Show Guppy phenotypical classes.  My breeding practices follow those conventional to any domestic breed across species with small refinements applicable to rearing Guppies.  In this case my breed of choice is a domestic Poecilia reticulata Lowersword strain.  What is the primary difference you may ask?  A pedigree strain if succesful, like those produced on any farm across domestic breeds, will persist in recognizable form for many years well past my time as a breeder.

A common theme often passed to me as a young breeder by old-timers basically said, "the sign of success for any breeding program is not how many ribbons are aquired in the show ring.  Rather how many herds and flocks your breeding program has founded or influenced along the way within your breed of choice"  To this end, I set out to several decades ago to recreate the modern image of  a Swordtail Guppy within the International Fancy Guppy Association (IFGA).  In the form of a linebred maternal pedigree breeding strain.  During the process I seemed to have expanded my initial goals.

To date my Lowersword strain has been directly sent or taken by myself or other breeders to over 40 US States including Hawaii & Alaska, Brazil, China, Japan, Taiwan, Thailand, Indonesia, Malaysia, Singapore, Vietnam, Australia, South Africa, Germany, Austria, France, Italy, Poland, Romania, Bulgaria, Norway, England, and Canada. Several other European & Asian countries slip my mind at the moment.

William Storrie, a noted and wise old Belted Galloway cattle breeder and acquaintance once stated, excerpt [Conservation of genetic endowment in a small (40 females/4 lines) nucleus cannot conserve the genetic variation of the breed. It is simply a snapshot at one particular moment of time from one specific viewpoint... …a reference point…].  As a pedigree breeder, I seek to show and promote only those individuals which are representative as a genomic snapshot of the actual breeding stock in my program. A reference point of those individuals utilized to reproduce the strain in a continuing fashion.

I maintain a linebred, and generally closed maternal pedigree breeding program over many generations. From which I simply show those individuals best suited for the show bench. Little different from any domestic pedigree breeding program across species. All breeding’s consist of several female X-link lineages and a single Y-link male lineage.  Yes, each and every male and even females in my breeding program descend from a single prepotant foundation sire.  One with the genotype needed to found a strong paternal lineage in a recognizable lowersword form.  Less than a dozen outside females have been brought in, to infuse novel color-pattern genes not already present, since inception of the current combined Lowersword strain ca. 2002.  In most cases, new female X-link genes were eliminated after infusion of desired autosomal gene(s) for color-pattern had been accomplished.

Contrary to many “Show Guppy” or "Commerical" breeders who set size and early maturity as the primary criteria, I do not make planned terminal outcross breeding's, from within established lines or via infusion of unrelated stocks, solely for the purpose of producing non-breeding, fast growing and large bodied F1 hybrid offspring destined for show or sale. Such individuals are genetic "dead-ends" that do not contribute to future generations, and are of no value in my fishroom or breeding program.

Nor, would they be representative of my pedigree breeding program.  A sound breeding program is one in which positive beneficial genes are identified through autosomal accrual.  While attempt is made to identify and eliminate negative genes before autosomal accrual can occur.  Selection of genes for both longevity and fertility are part of this process in a pedigree breeding program.

Three month old Asian Blau Blond Bunt Ls male.

Longevity and fertility in my Lowersword strain are not solely the result of physical attributes, i.e. "moderate body size & a lighter caudal weight". Just as lack of longevity and fertility in Broadtails are not solely the result of physical attributes, i.e. "large body size & a heavier caudal weight".

Nor is longevity and fertility in my Lowersword strain solely the result of reduced environmental inputs with age, i.e. reduction of dietary inputs, water temperature reduction, or water changes. All fish, regardless of age, receive the same daily feedings of live (Baby Brine Shrimp – BBS) and prepared flake food mixes. Each and every tank receives the same feeding regimen based solely on the total volume of fish it contains.  All ages groups and sexes are maintained in haphazard fashion in all rows, racks and tiers without regard to temperatures.  All tanks recieve the same percentage of water change each week.  Breeders and show fish tend to be housed on higher tiers, with higher corresponding temperatures, for ease of viewing.

Yes, this may seem counter-productive to accepted practice for longevity and fertility of current individuals in optimum age-based form used to breed or for show.  As the majority of my show fish, both males and females, are actively engaged in breeding groups.  However, I wish to identify those individuals that fail to thrive under moderately high inputs and eliminate them from the gene pool.  I seek to identify those who thrive in mixed age breeding groups well into advanced age.  Remove those that are obviously infertile, become "chesty" or otherwise "obese" and cannot metabolize the same ration as efficiently as other male and female cohorts of various ages in the same settings. 

Longevity and fertility are in part based on positive selection for specific aspects of fecundity over multiple generations.  In the case of my Lowersword strain 80-100+ filial generations since prior noted inception date of 2002. Generations are not always sequential, i.e. each breeding is not intended to increase the filial count. Many breeding’s involve either paternal (BC1) or maternal (BC2) backcrosses. All of which are common practices in domestic pedigree livestock breeding.

Grey Vienna Emerald male expessing Type2 Bunt (Bu2)
erythrophore based coloration over iridophores.

Often, a percentage of breeding’s are linear using the same generation in multiple breeding’s over a period of 2-3 years. It has long been my feeling that if current breeding results are positive, then there is no need to progress to the next filial generation. As you risk the chance of a decrease in one or more aspects of fecundity within a small gene pool. My Lowersword are maintained by numerous breeding’s each year in no less than 40 tanks and currently 70 tanks. It has run as high as 80-100 tanks in the last few years. This is still a small number when 650 breeding age females is considered the bare minimum to maintain a small population.

Many productive and/or prolific breeding groups are kept intact. Fry are saved over multiple parturitions, i.e. “long-cycle breeding” is practiced. Resulting in a larger potential breeding population with mixed attributes. As opposed to “short-cycle breeding” practice geared toward maximum number of same age males & females for a show season. Which is often based on saving fry only from the first 1-2-3 parturitions. Then culling all brood females and no longer utilizing sires for additional breedings. 

Why is long-cycle breeding practice important?  It forms the basis for linking both longevity and fertility together within your males and females.  Short-cycle breeding schemes can impose negative selection on both longevity and fertility in very few generations. Over time, producing a smaller breeding population with a narrow set of homogeneous attributes.  One which relys on frequent outcross of stocks shared among breeders in compatible breeding schemes to mask weaknesses.

This is not to say a breeder should not make use of limited short-cycle test breeding’s and save a litter or two for evaluation. Retaining results if superior and culling when inferior. To once again reference William Storrie, excerpt [The top two [bull calves, sic each year] are mated to four of the worst heifers (two each) and the rest are fattened and killed…]. A practice which I mimic with many of the best top end males I rear out that were not initially selected to be included in long-term breeding groups.  If you take the time to raise them out, test breed them in the interim.  Retain and infuse positive results into your breeding program.

3 month old Grey Bunt Ls males expressing
both Type1 & 2 Bunt (Bu1 & Bu2) coloration.

3 month old Grey Bunt Ls male expressing
both Type1 & 2 Bunt (Bu1 & Bu2) coloration.

       3 month old Grey Bunt Ls males expressing both Type1 & 2 Bunt (Bu1 & Bu2) coloration.

While the results of my simple test for longevity & fertility are somewhat anacdotal in nature, it does provide insight into current extreme age range for both traits in my linebred breeding population.  These two aspects of fecundity have not been reduced or lost over the years.  Either within my breeding population or as historically reported in P. reticulata (Comfort, Alex 1961).  While not all males, or females, will achieve this result, I am pleased to know a percentage still do.  That is the intent.  As based on practices which I have long adhered to in pedigree cattle, sheep and fish breedings over the last 4 decades.  I am even more pleased to know that these two traits appear to have been succesfully linked together, and that I'm not simply retaining sterile males and females into old age.  Can you say the same for your breeding population?

References:

Storrie, Wm., 1993 Some Observations on Belted Galloways, Correspondence from William Storrie, Netherwood Farm, Bathgate, West Lothian

https://beltie.org/articles/some-observations-on-belted-galloways.php  Last checked 8.13.2024.

Comfort, Alex. "The longevity and mortality of a fish (Lebistes reticulatus Peters) in captivity." Gerontology 5.4 (1961): 209-222.

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Final thoughts I will leave to the late Bill Storrie, excerpt [Most deleterious genes involving fitness are recessive… …breeders nearly always opt to mask their effect by outcrossing. But inbreeding doesn’t MAKE bad genes. It is the process that FINDS bad genes that already exist in the genetic endowment (the genome of the breed or species).  And allows breeders to eliminate them, or reduce their frequency.  If bad genes exist at a high frequency they will be found quickly: at a low frequency only after many attempts to uncover them.  If none EXIST none will be FOUND.] 

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WHY DO GREEN-BLUE-PURPLE GUPPIES SUDDENLY APPEAR IN DEDICATED STRUCTURAL COLOR BREEDINGS?

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.  

References:

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.

http://www.pr.bioflux.com.ro/home/volume-7-1-2017/

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.

http://www.pr.bioflux.com.ro/home/volume-7-1-2017/

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Things getting out of hand in your fishrrom?

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

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