Freshwater and Marine Aquarium June 1979
Pingu – A Remarkable New Guppy Strain

Ten years ago, Marine Biologist David Liebman had a small tailed fish with a single pink dot on the peduncle. Today, 62,280 test crosses later, he has created a matchless colored guppy strain. This new strain is called Pingu meaning Pink Guppy.

David Liebman

This entire strain originated from a male guppy named Spot Light. Spot Light had a single highly intense dot on both sides of the caudal peduncle. So highly intense and bright was that single dot, that the fish that sported it caught my eye and was singled out instantly from a tankful of many other guppies. The fish stood out as prominently as a bright light does on a dark night.

Being a guppy nut from childhood, and with a strong interest in genetics, I let my vivid fantasy go wild. What would a guppy look like if that color could be carried into the tail? Would that ever be possible?

Immediately the first test cross was made by crossing Spot Light with his sister. In time more male fish were produced with that dot. One day a fish appeared with the dot elongated into the shape of a comma on the peduncle. Now all dotted males were culled, so that only Cousin Comma would be allowed to hit the females.

The fish were bred in quantity to allow a full range of genetic expression of the gene for this color. Through selective breeding, the comma elongated to form a pink band, or ring, around the peduncle (the peduncle is the part of the fish that is posterior to the anal fin, and anterior to the tail).

For some time no further improvement followed. And just as the frustration of 'no-progress' started affecting me, there appeared a new male with two parallel bands. On a latter fish, the color fused between the two bands. The fish with this mass of color was named Pink Amoeba. Time marched on, and fish appeared with completely pink caudals, but without pink tails. The next improvement was pink at the base of the tail. Ever so carefully fish were chosen with more and more pink in the tail until, finally, a fish with pink on the body as well as on the tail was formed.

It must be remembered that all of these fish had small tails, similar to ordinary common guppies. Tail size was secondary to color in those early days — extensive color being the primary goal. Once good coloration was achieved, the time had come to develop a better tail on this new strain.

A number of world renowned breeders helped at this critical point in strain development. Bob Maxwell donated fish from his blackstrain. A number of other world renowned breeders including Mike and Alice Regent, Louis Wasserman, Ted Henning and Ron Ahlers, spent many hours helping in the selection of guppies from their very best stock. These fish were to be used for Pingu out-crosses. Among the many strains used in the development of the new tail, dorsal, and larger body were some of the best of the following:

Top Heavy was the name given to the first fish to display extended tail rays concentrated at the top area of the tail. Likewise, Bottom Heavy had extended tail rays on the bottom of his tail.

Highly metallic reflective male, Iridescent Irving, with color brighter than any before him, made an appearance as did The Umbrella with his much improved development.

Pingu® has a family album of outstanding and interesting members, including the following fish. (For identification purposes, fish names were applied according to unique attributes.)


  1. Spot Light — The guppy that started the strain with an intense pinkish spot. Bred through seven generations of grandchildren to F7 until Cousin Comma appeared.
  2. Cousin Comma — The pink spot elongated into a comma shape.
  3. Benny Band — Comma shape extended into a pink band.
  4. Twin Bar — two pink bars.
  5. Pink Amoeba — Bars fused into a mass of color.
  6. Pink Caudal — Had a pink caudal (area in front of the tail).
  7. Top Heavy — Extended tail rays on top of the tail.
  8. Bottom Heavy — Extended tail rays on bottom of tail.
  9. Iridescent Irving — Highly reflective body.
  10. The Umbrella — Large dorsal (top fin) development.
  11. Freddie Flag Tail — Enlarged tail, shaped like a flag.
  12. Pretty Pingu® Paula — First female to develop male coloration.
  13. Blue Boy — Blue-purple pigment expressed.
  14. Pingu® Pete — The best fish to date, with the best features of all crosses.

The above fish were chosen to be breeders. Each was selected from as many as four thousand guppies. Excess non-pink hybrids were sold to pet shops and pink culls were eliminated.

How did this basic color become so pure and intense? No, it was not hit or miss, but through careful, methodical selection of the pinkest of pinks for future breeders. Over the years at least three different artists and some college art instructors helped in this selection.

An artist's eyes are highly sensitive to subtle chromatic differences. Artists also helped in selecting for brightness and intensity. Some pinks are so bright in color that anyone asked to comment on their intensity invaribly chooses the following words: ''hot," "brilliant," "iridescent," "metallic,'' "sunshine,” "fluorescent," "vivid," etc.

Pingu® displays all of the above color qualities and intensities, but what is the secondary color?

One of the artists said, "Every time one of these living diamonds moves, the colors white, orange, red, satin pink, peach, turquoise, aquamarine, metallic blue, iridescent green, and yellow appear to sparkle, vibrate, and jump off the fish."

Pingu® is the first guppy in many years to have a new fin and body color; this is an entirely new color classification. Think how many years have passed since new guppies have been introduced. This newly developed half-pink coloring could well surpass in popularity the sensational half-black and Cobra guppies of past years. Pingu®, the half-pink guppy will open doors to opportunity in a rapidly growing pet industry, one which already boasts annual sales in excess of five million dollars in sales.

Fish judges' eyes will open wide with excitement when unexpectedly and for the first time in their life, they will discover fluorescent pink guppies among the usual guppy entries. Many years have passed in the U.S. since there has been a guppy this different. Which Pingu will win at tropical fish shows? Probably the first ones entered!

Soon creative breeders will start producing new color strains and put different colored tails on the fluorescent pink body. For some raising and creating new color varieties of Pingu® will become a real financial enterprise.

This strain is highly variable in size and secondary coloration. The average size is larger than ordinary guppies, but a large fraction are even bigger and may be properly termed Giant guppies. Strong and solid-colored white, yellow, platinum, green, blue, peach-orange, and red tendencies are appearing on many different individuals. The reason no two Pingu® are exactly alike is because Pingu® are carefully crossed with each other so that most adults carry genes necessary for the production of the above overlay colors in an assortment of slightly different combinations. Generally, many variations are expressed in an average spawn. This additional color variation is valuable to the breeder, or developer, with a sharp eye offering more possibilities to choose a direction in which to breed. Many new and valuable breeds could come of this strain with further selection.

Many of the world's best available guppy strains have been combined in the production of the present day Pingu®. Locked within Pingu® gene pool is the genetic information that produced the outstanding traits of the original award winning strains. The key that unlocks these award winning traits is simple out-crossing.

Now — and this is important — anybody can create hybrid guppies. The best fish from one strain are bred with the best fish from the other strain. (Note: the males must represent one line bred strain, the females another.) For years, breeders have produced trophy winning show fish in just this manner.

In test out-crosses (Pingu® crossed with other inbred guppy strains) results are often quite startling. The first generation tail color is usually different from either parent and frequently there are unusual body markings . . . and better yet, the hybrids are often better than either parent in:

  1. Having greatly increased tail angle to about 90°.
  2. Growing into "giant" guppies, one-fourth to one-third larger than ordinary guppies.
  3. Having, and displaying, exceptionally large and wide dorsals.

An experimental test cross between a pink male and red female is diagrammed.

Basic Genetic Terminology Used In The Following Example

An inherited factor that determines a biological characteristic of any organism is called a gene. In guppies, as in most other animals, genes are paired and are recognized by their production of a particular biological effect such as tail color. The two individual genes in a pair are called alleles. In some cases, alleles are identical (homozygous); i.e., a red guppy strain may carry two identical alleles r and r or (rr) or (pp) in a pink guppy strain. When the gene pair has two different alleles present as a single gene pair p and r, the guppy is heterozygous for that gene pair. In some cases such as a hybrid cross resulting from a (red rr x pink pp), we end up with mostly half-black body fish (rp), quite unlike either parent.

pp = true breeding pinks, pink dorsal. (homozygous).
rr = true breeding reds, red dorsal.
rp = (heterozygous) a hybrid of (pp x rr).

P1 (Parents)
Pink Male X Red Female

F1 (First Generation) Offspring
All rp hybrids; 98% were larger than P1

rp Hybrid Breakdown
80% had half-black bodies. Of these, 100% had blue tails with pink polka dots.
10% had wild coloration grey bodies. Of these, 100% had blue tails with pink polka dots.
5% had unusual black splotches (larger than dots) on the male's body. All had solid dark blue tails.
5% had gold bodies with black tipped scales (bronze).

If these half-black body hybrids are crossed with hybrids of the same type, young are born in the following ratios:

25% are pp (pink) similar to P1 parents.
25% are rr (red tail, red dorsal) similar to P1.
50% are rp, again half-black body hybrids.

From the above example and chart we learn that if we always cross hybrid X hybrid the result (with respect to these particular characteristics) will yield three of more types of guppies from a single pair. This technique is especially valuable when one desires to raise several types of guppies but only has space for one type. From my experience, I find the only two basic qualifications to be that.

(1) The hybrid heterozygous fish produced from the cross should be observably different from either starting strain.

(2) If you pre-test cross and only use the heterozygous hybrid fish for breeders you will usually produce about 50% heterozygous fish and about 25% similar to each of the initial homozygous starting strains.

If you become involved in developing a new type of fish, or if you enjoy breeding show guppies, do what many other breeders do with the extra fish that are not show quality — sell them! Many pet shops are looking for good quality freight-free healthy fish and will often pay high prices to obtain them. The better your initial stock the more money you can charge. The pet shop personnel will, in turn, sell them at a profit to customers. Beautiful large hybrid guppies are often desired for peaceful community tanks in many types of offices, for relaxation purposes, especially those of doctors and lawyers, home community tanks, etc., and for other non-breeding purposes. If the pet shop has a call or request for true breeders, sell fish from your original true breeding strains at even higher prices. In all fairness, never sell guppies as true breeders, unless you know it to be a fact. If you are honest, you will gain respect, repeat business, and also receive recommendations to other pet shops for increased business.

Selection standards are so high that no more than the best 15% are kept, and these only in limited numbers. Since the supply is limited, and the expected demand is high, no more than four fish will be sold to any one individual. This will insure that everyone will have an equal opportunity to obtain and enjoy these fish, until they run out. This will be done in the interest of fair distribution.

These guppies were developed at great expense, over a ten year time period. After 62,280 experimental test crosses had been made to attain a matchless guppy, one male and one female were selected as the ultimate parents.

The resulting female was named, "Pretty Pingu® Paula"; the best male, "Pingu® Pete." All future Pingus® will be direct line descendents from Pete and Paula Pingu®.

I wish to give my thanks to the following individuals. Each was altruistic to me in one way or another during the development of Pingu®: My parents and brothers, my girlfriend Rona, Midge Hill, Dr. J.M. Schoenfeld, Ron Ahler, Johnny Lockhard, Sid Garfield, Dr. Tony Provenzano, Gale Brown, Philip Willes, Ed Taylor, Bob Maxwell, Clarence Garrison, George Clark, Bob Carper, Ted Henning, Alan Cogan, George McCrosky, Louis Wasserman, and Mike Regent.

CybeRose note:

I read this article when it was first published back in 1979. The brilliant pictures blinded me to the blatant advertising.

I spent a lot of time — probably too much — trying to figure out just what was going on. Liebman didn’t help any with his bogus Punnett squares. Red is a pigment. Pink is presumably a structural color due to the arrangement of guanine crystals. The color shifts as the fish move, just as the color seems to change when we look at a diffraction grating or oil slick from different angles. In other words, red and pink are not alternative characters that can be paired in a Punnett square. Please note that before Pretty Pingu Paula, no females expressed pink iridescence, though red females were common. Furthermore, some modern (2009) strains combine red and iridescent pink in the same fish.

The half-black trait is dominant, so at least one of the parents must have been half-black. Red is associated with reduced iridescence — otherwise the structural color would predominate. The blue fins polka dotted with pink indicate that pink irridescence had lower expressivity (was expressed less widely) than blue irridescence. If blue irridescence is coupled with reduced irridescence, the underlying pigment (yellow, red or black) is clearly visible. And when such a fish is mated to an irridescent pink, the irridescence dominates, but is mostly blue with islands of the alternative structural color.

In the pink and red strains, irridescence is reduced to blotches. So is the red, which tends to be blotchy anyway, especially when it is expressed in the forward part of the body.

Details aside, the pink trait in guppies is another instance of how real breeding works. In the first half of the 20th century (and later), Mendelianists — especially the fruitfly breeders — imagined that all heredity could be reduced to a shuffling of mutant defects. Some, such as Bridges (1931), even advised plant breeders to stop wasting their time breeding plants, and instead concentrate on fruitflies. In his uninformed opinion, the only way for plant breeders to make any kind of progress was to wait patiently for desirable "mutations" to occur, then to isolate and multiply the new types. Apparently he was unaware that real plant and animal breeding often begins with a bare hint of a trait (e.g., a spot, tinge or streak of color; a slight waviness to the margin of leaf or petal). The breeder must then coax the slight tendency into greater expression. Once the trait has been perfected, it sometimes behaves (more or less) like a "unit character". To the old time Mendelianists, this was "proof" that the trait had appeared as a simple gene mutation. All the breeder had to do was isolate the "pure strain" from the heterozygous mixture. Nothing to it! Nevermind that it took Liebman 7 guppy generations to get from Spot Light to Cousin Comma, and many more before the pink irridescence began to extend onto the tail fin.

BTW, I suspect that the 62,280 "test crosses" are the products of controlled matings, not the matings themselves. In other words, Liebman raised over 62,000 fish, most of which were discarded.

As Darwin explained, "If selection consisted merely in separating some very distinct variety and breeding from it, the principle would be so obvious as hardly to be worth notice; but its importance consists in the great effect produced by the accumulation in one direction, during successive generations, of differences absolutely inappreciable by an uneducated eye—differences which I for one have vainly attempted to appreciate."

Fish Heredity

Castle, 1914: Piebald Rats

Other examples of "Darwinian" selection at work.