By Hannah Nielsen
Which guppy is right for you — and why the names are so confusing
You searched "guppy fish types" and landed on a hundred different answers, because everyone lists guppies a different way. One site sorts them by tail. Another by colour. A third treats Endlers as "just small guppies". None of them tells you the one thing that actually saves you money: the type changes the looks and the price, never the care.
I'm Hannah Nielsen — I shoot aquarium photography for a living, which means I spend my days nose-to-glass with small, fast, brightly-coloured fish, and guppies are the busiest subjects of the lot. After enough hours behind a macro lens you stop seeing "a guppy" and start seeing the three separate things every guppy name is really telling you.
This is the guide we'd give a customer who points at the livebearer tanks and asks, "what's the difference between all these guppies?" The honest answer is that there are three independent ways to classify a guppy — by tail shape, by colour-and-pattern strain, and by species (fancy guppy versus Endler) — and a single fish is described by all three at once. A "red cobra delta" is one colour strain, one tail shape, one species, bundled into a label. Decode those three axes and the whole shop wall stops looking like chaos.
A male Blue Moscow guppy (SKU 6082). "Moscow" is a colour strain — a deep, solid metallic body — and this fish also has a delta tail and is a fancy guppy (Poecilia reticulata). Three labels, one fish. Photo: Tropical Fish Co.
Fun facts — the stuff most UK guppy guides skip
- Endlers weren't a recognised species until 2005. John Endler collected them in Venezuela in 1975, but they were only formally described as Poecilia wingei — separate from the common guppy — three decades later [2].
- Guppy colour is mostly written on the Y chromosome. That's why the males carry almost all the pattern and the females stay plain: the genes for those bold reds, snakeskins and cobras are largely sex-linked [3].
- Fancy guppies and Endlers interbreed and produce fertile hybrids. It's the single reason pure Endlers are getting harder to find in the UK trade — one shared tank and the lines blur within a generation [4].
- The wild guppy is one of the most-studied fish on Earth. Its colour genetics and mate-choice behaviour fill an entire Princeton monograph — guppies are a textbook model for sexual selection [3].
- Hard British tap water is a gift for every guppy strain. Livebearers evolved in hard, alkaline, mineral-rich water — exactly what comes out of the tap across most of England [5].
How to read a guppy label
Once you know the three axes, a shop label decodes itself. Take three fish from our own tanks:
- "Assorted Male Guppy (triangle mix)" — triangle is the tail (delta), male tells you it carries the colour, assorted means a mix of colour strains. So: delta tail, fancy guppy, various colours.
- "Red Cobra male" — cobra is the colour strain (the net pattern), red is the dominant colour, male again the colourful sex. Tail shape unstated usually means delta.
- "Endler tiger" — Endler is the species (Poecilia wingei, not reticulata), tiger is the pattern name. Small fish, natural tail.
Read in that order — species, then colour strain, then tail — and you'll never be confused by a livebearer tank again.
Guppy types explained — the three axes
By tail shape
The first axis is the fin silhouette. UK shops stock far more delta/fantail guppies than anything else, because that wide triangular tail breeds reliably and shows colour best. The strains we stock are nearly all delta-tailed.
| Tail type | What it looks like | How common in UK shops | In our stock |
|---|---|---|---|
| Delta / fantail | Wide triangular fan — the classic guppy tail | Very common | Most strains, incl. the "triangle mix" (6054) |
| Veiltail | Long, flowing rectangular tail | Common | Occasional show males |
| Swordtail (top / bottom / double) | One or both tail lobes drawn into a point | Uncommon | Rotating lines |
| Lyretail | Two symmetrical curved points | Uncommon | Rotating lines |
| Roundtail / spadetail | Small, rounded — closest to wild guppies | Common (Endlers) | Endler strains (6061, 6446, 6415) |
Tail shape is the loudest visual cue but the least important for care. A delta and a roundtail want identical water.
By colour-and-pattern strain
The second axis is the body-and-fin pattern, which has its own vocabulary. This is where most of the famous strain names live — and where our in-stock fish differ from one another.
| Colour strain | The defining marking | Strains we stock |
|---|---|---|
| Cobra | Fine vermiculated "net" pattern over the body and fins | Green Cobra (6048), Red Cobra (6095) |
| Moscow | Deep, solid, metallic single colour | Blue Moscow (6082) |
| Solid colour | One saturated body colour, minimal pattern | Red (6070), Yellow (6071) |
| Mixed / assorted | A deliberate mix of colours sharing one tail shape | Triangle mix male (6054), female mix (6053) |
| Red-cap | Pale body with a solid colour patch on the head | Red-cap female (6715) |
Cobra and snakeskin patterns are among the hardiest looks; the most extreme solid show-lines can be a touch more delicate [6].
Fancy guppy vs Endler — two species, not one
The third axis trips up the most people, so it gets its own section. A fancy guppy is Poecilia reticulata — the familiar fish that reaches about 6 cm and has been bred into every tail and colour on the shop wall [1]. An Endler is Poecilia wingei, a genuinely separate species only described in 2005, and it is smaller, brighter and closer to a wild guppy in shape [2].
| Feature | Fancy guppy (P. reticulata) | Endler (P. wingei) |
|---|---|---|
| Adult size | Up to 6 cm | Male 2.5 cm, female 4.5 cm |
| Colour | Huge range, often diffused over big fins | Brighter, sharper, more concentrated |
| Tail shapes | All (delta, veil, sword, lyre…) | Mostly small natural shapes |
| Best tank size | 40 L+ | 20–40 L (great nano fish) |
| Interbreed? | Yes — with each other and with Endlers | Yes — hybridises readily with guppies |
The practical upshot: if you have a small or nano tank, a group of pure Endlers looks sharper than standard guppies and stays small. If you want the big flowing fins and the widest colour palette, fancy guppies win. And if you want either to stay pure, never keep them in the same tank — the two species interbreed freely and the fry blur the line within a generation [4].
Because guppies and Endlers produce fertile hybrids, decades of shared shop and breeder tanks have steadily introgressed guppy genes into the Endler trade. True "N-class" (no-hybrid) Endlers now mostly change hands through livebearer clubs and dedicated breeders rather than general retail. If absolute purity matters to you, buy from a single documented line and keep that line on its own — one stray fancy guppy undoes it [4].
Do the types need different care? (No — they're identical)
This is the section to remember. Every guppy type on this page — every tail shape, every colour strain, and both species — wants exactly the same care. The label changes the price tag and the photograph. It never changes the husbandry [1].
A Green Cobra, a Blue Moscow, a plain red male and a group of Endlers all want the same thing: 22–28 °C, hard alkaline water (10–30 dGH, pH 6.8–8.5 — most UK tap water), a planted tank of 40 litres or more, and a varied omnivore diet of flake plus frozen foods. Don't overthink it per strain. Get the water and the tank right and any guppy type thrives.
The one genuine nuance: the most heavily selected show-strains — extreme veiltails, big-eared lines — tend to live a little shorter and are a touch less hardy, because the breeding for dramatic finnage has compressed the healthy lifespan [7]. For a first guppy tank, a lively cobra or a group of Endlers is more bulletproof than an elaborate long-finned male.
Care basics — same for every type
Because the care is shared, you only ever learn it once. Guppies are tropical livebearers from hard, warm, mineral-rich water, and that's what makes them such a good match for British tap water — across most of England the water comes out of the tap exactly as they like it [5]. Give them:
- A planted 40 L tank or larger. Floating plants and fine-leaved stems give fry somewhere to hide and the adults somewhere to feel safe.
- 22–28 °C, stable. A small heater does the job; stability beats chasing a perfect number [1].
- Hard, alkaline water. No chasing soft-water parameters — dechlorinate UK tap water and you're done.
- A varied omnivore diet. Quality flake as the staple, plus frozen bloodworm or brine shrimp a few times a week.
For the full husbandry deep-dive — sex ratios, breeding control, hard-water care and tank mates — read our complete guppy guide, or the single-species guppy care guide. If a nano tank suits your space, the Endler care guide covers the smaller species in detail.
A Tiger Endler (SKU 6446) — Poecilia wingei, a separate species from the fancy guppy. Note the sharper, more concentrated colour and the smaller, natural tail shape compared with the Blue Moscow above. Photo: Tropical Fish Co.
When your guppies arrive — livebearer delivery & acclimation
Guppies and Endlers are among the hardiest fish in the hobby to ship, but they're still tank-bred animals that have only ever known a narrow water-chemistry range. The acclimation routine matters [7]:
- Open in a dim, quiet room. Less light means less stress on arrival.
- Float the sealed bag 15 minutes. This equalises temperature only.
- Drip-acclimate ~30 minutes at one to two drops a second. Guppies tolerate a wider chemistry range than sensitive soft-water fish, so they don't need the long 45-minute drip a cardinal tetra would.
- Net into the tank — don't pour the bag water in.
- Lights off for an hour, no feeding for 12 hours. Resume normal feeding the next morning.
Every order ships with a licensed live-animal courier and our live-arrival guarantee. Photograph the unopened bag within two hours if anything arrives in poor shape and we'll put it right at our cost.
Don't judge a strain's final colour in the first hour — transport stress makes even a vivid Red Cobra look pale until it settles in.
Where strain-keepers gather in the UK
Guppy and Endler strain-work is more fun — and far cheaper — once you've found people to swap lines with. Pure-strain breeding pairs change hands at club meets for a fraction of specialist-retail prices, and the experts there will tell you which lines actually breed true.
- The Federation of British Aquatic Societies (FBAS) lists around 70 regional UK fishkeeping clubs, many with active livebearer sections [6].
- Reddit's r/Aquariums and r/livebearers carry weekly UK-specific threads on strain genetics and where to source clean lines.
- Specialist livebearer breeders are where documented, single-line Endlers and rare guppy strains (Moscow blacks, snakeskins) really live — retail tanks are mixed by nature.
This is also the honest answer to "which strain should I get": go and look at fish in person, pick the colour that genuinely stops you, and choose an active, clear-finned individual over the most dramatic tail in the tank.
Related reading
If you're choosing between the sexes rather than the strains, our female guppy guide covers all-female tanks and breeding ratios, and the complete guppy buying guide is the broader care-and-stocking deep-dive.
- Shop: the guppy hub for fancy strains, or the wider livebearers hub for guppies, Endlers, mollies and platies in one place.
- Learn: the guppy care guide for husbandry, and the Endler care guide for the smaller species.
- Compare: female guppies and the full guppy guide to decide sex mix and strain together.
The References block renders automatically below from the frontmatter —
every <CiteLink> above points at a verified source there.
