How to breed perfect guppies


Guppy guru Derek Jordan offers advice to experts on how to keep and breed top quality guppies.

There is a popular belief that Guppies are a hardy fish which can be neglected, yet still flourish, and that they are a fish for the beginner.

Now although many fishkeepers started with Guppies, over the years the species has encountered some quite bad press, mainly due to overbreeding and inbreeding issues.

However, there is absolutely no reason why you cannot have a perfectly healthy tank of these stunningly coloured fish. As Guppies are easy breeders, with a little care you can optimise your chances for a healthy, vibrant stock.

Getting down to basics

A breeding set-up should be designed for easy maintenance, especially as chances are you'll end up with loads of tanks! I keep my breeding tanks in the bare mode, so no plants or gravel.

Small tanks will suffice: 25 l./5.5 gal. for a breeding trio and 36-45 l./8-10 gal. tanks for growing on. As a rule of thumb, allow 2.5cm/1" of fish per gallon to allow your fish to achieve their full potential.

Some enthusiasts opt for higher stocking levels, which is fine if you carry out more frequent water changes. Don't push your luck as you could end up with stunted, poor quality fish.

As for filtration, I opt for air-driven corner filters or sponge filters with plenty of airflow. And I mean plenty, such that the water above the filter looks like it is boiling.

Such a strong flow serves one purpose; it forces the fish to develop strong muscles, especially in the caudal peduncle. This helps the delta varieties hold their tails in a more natural way and not look like the tail is too heavy, making the fish looks somewhat bent.

Ideal water parameters are pH 7.2 (normal range 6.8-7.8); 8-12 degrees GH (normal range 4-20 degrees GH); and a temperature for fry of 25.5 degrees C/78 degrees F; juveniles (four to eight months) of 24.5 degrees C/76 degrees F, and adults somewhat cooler at 23.5 degrees C/74 degrees F (normal range 10-29 degrees C/50-85 degrees F).

A Guppy needs 12 hours of lighting each day, best provided using 30-40W fluorescents mounted above your tanks. Don't be misguided into thinking that intensity matters.

Duration is far more important, and a simple timer will ensure that the lights are turned on and off at the right time.

Care and maintenance

Guppies are omnivores, so offer as wide a range of quality flake food, live and frozen foods as possible. It is also better to feed small amounts every few hours than one gigantic feed.

Frozen and live food are digested easier than flake food, so can be fed in larger portions. As a guide, if your fish do not eat all the food you put in the tank in two minutes, chances are you're overfeeding them - or they could be ill.

If you overfeed your Guppies, the excess food passes through the gut without being properly digested and will foul the tank. Try to avoid feeding a diet rich in protein as this can cause constipation, causing a build-up of toxins in the fish's gut.

Which leads me to the point that fish create waste, and this waste creates both good and bad bacteria. If waste builds up within the tank, eventually the bad bacteria will outnumber the good and the water conditions start to fail.

Correspondingly, your Guppies' fins and health will deteriorate. Regular water changes are a must. I carry out weekly changes of 25%.

Know your strain

Before you attempt to breed Guppies, you need to understand the characteristics of your chosen strain - each is unique.

This can be tricky if the person you bought your fish from does not know its genetic make-up. However, all is not lost as close observation and the keeping of breeding logs will reveal much.

The first step is to note all the characteristics of your stock. For instance, does the colour have a uniform look or is it more intense in specific areas? What about fin shapes? Find out what the ideal shape should be.

Fellow enthusiasts are always a good source of information. Find out if your strain carries the traits you want on the X- or the Y-chromosome. The Internet can be very useful in helping you trace the genetic make-up of your fish.

Obviously if you have a specific goal, eg. solid black fish, this makes it easier to organise your tank space and select the fish you intend to keep out of each litter, ie. as much black in the body, or even a particular dorsal or caudal shape.

Never, ever keep just the one pair of breeders: disease happens, no matter how careful you are, and you do not want to put those years of hard work in jeopardy by losing just two fish. Ideally, aim for two or three trios in separate tanks.

Keep those records

Your breeding log should have the following information:

Identity: Give each breeding pair or trio an identity number, so your first pair is number 1, your second number 2 and so on. This allows you to trace the lineage and any crosses that have been made.

Sex: M or F for male or female.

Colour/strain: eg. half-black red delta or yellow snakeskin.

Generation: Start with P for parentage, followed by F1, F2 etc.

Cross: Are the fish being bred brother to sister (siblings), parents to daughter or son (backcross), or to a genetically related strain (outcross)?

Parents: What was the identity number of the parent fish?

DOB: Date litter was dropped. This is useful to work out the age of fish for breeding and to track their progress for finnage and colour development, which varies according to strain.

Breeders produced: Did they produce any litters with potential breeders?

Notes: Allow plenty of room for observations about when the fish started to sex out, ratio of males to females, growth rates, etc.

Always mark the tank with the ID number and the date the litter was born. Masking tape is good as you can easily remove this and attach it to the fish's new tank if you move it.

Line breeding

The problem with successive inbreeding is that each generation loses some genetic diversity. Line breeding helps overcome this and keeps a strain true.

Basically it combines inbreeding with a crossing from a related line every few generations, ensuring healthy Guppies for years.

The most common method is to break your strain into two lines for inbreeding. Then after three generations, cross the lines. A simple illustration of inbreeding is:

Line 1 Line 2

P1 M F P1 M F

F1 M F F1 M F

F2 M F F2 M F

Cross Line 1 F2 female (F) with Line 2 F2 male (M), and Line 2 F2 F with Line 1 F2 M.

Guppies are typically four months old before they can be bred, so to repeat the above for three generations would take about 12 months before your first cross. Also the more lines you run, the more diversified your gene pool will be.


This refers to the mating of two unrelated Guppies. While inbreeding reduces the variations of your offspring and line breeding helps keep your gene pool intact, out-crossing corrects or adds a gene to your strain.

For example, you may want to get a bigger dorsal fin, improve the colour or rectify a defect in the caudal fin. Or you may even want to create a totally new strain.

Having said that, out-crossing is best not attempted by a novice for if you get it wrong, you could lose the strain traits altogether.

With out-crossing, it's critical to ensure strains are compatible - some colour strains mix, others don't. For instance, crossing a variegated snakeskin with a half-black red results in a very mixed-up Guppy. You really need to keep the original strains pure.

Out-crossing demands plenty of tank space and patience to carry out the required backcrosses to end up with the results you want. You'll need to use established strains whose genetics are stable, meaning that all offspring look identical.

Finally, try the cross both ways - female to outcross strain and male to outcross strain; you may not know whether the trait you want is X- or Y-chromosome linked.


This is where you breed, say, the male of a strain that you want to rectify a problem back to one of his daughters from the outcross, or the female of the strain back to her son from the outcross.

The aim is to restore the strain to its original format, but with the trait fixed.

You may have to perform this a few times. The way to check is if the sibling-to-sibling mating produces replicas of the parents with the trait fixed.

Who was first?

The Guppy takes its name from Rev. Robert John Lechmere Guppy, a conchologist, geologist and clergyman living in Trinidad.

Although he is credited with discovering the wild Guppy in 1866, Spaniard De Filippi found the fish in Barbados in 1862 and labelled it Lebistes poeciliodes.

However, even earlier in 1857 and 1858, amateur German biologist Julius Gollmer found Guppies near Caracas, Venezuela. He sent these fish to the Imperial Prussian Academy of Science, Berlin.

The ichthyologists were apparently not impressed, gave Gollmer only a small reward and then promptly filed the specimens in its archives. There they remained until 1859, when Wilhelm Karl Hartwig Peters, head of the ichthyology department, wrote a scientific description of them.

Unfortunately, the jars were not well labelled and he only described the females as belonging to a new species, Poecilia reticulata. Some time after 1866, the males were found and labelled Giradinus guppyi. The females later adopted the name of the male counterpart.

The scientific name has undergone a number of revisions over the past 100 or so years, finally settling on Poecilia reticulata (Rosen and Bailey, 1963). Rosen and Bailey also included Mollies in the genus.

The pioneer

Great Britain's pioneer in the fancy Guppy world was W. G. Phillips, born in 1883. During the Second World War, he sold his excess Guppies to a shop in London.

Some months later, he returned to find that a few remained and had bred, with some of the offspring having unusual tail shapes. He took these home and over the next few years, perfected the now familiar Coffer Tail shape.

Phillips created the British Guppy judging standard, from which all subsequent judging standards have been drawn. He also developed and sent overseas the English Leopard Guppy or English Lace Guppy, which may have been the original source of all Snakeskins.

Phillips won over 500 awards for his Guppies, and his house in Kenton was a shrine to the enthusiast. He was not a secretive man but freely shared his Guppies and ideas, leaving behind a huge legacy today.

Did you know?

The word 'Poecilia' means 'variegated' and 'reticulata' refers to the lacy pattern that is formed by the overlapping scales on the Guppy's body.

The Guppy has been called the Missionary fish as it has converted many to the hobby.

The Coffer Tail Guppy got its name from the fact that it resembles the South Wales miner's shovel.

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