Betta Varieties Explained
Fin types, body forms, and how to choose the right fish
...because the betta that catches your eye and the betta that suits your tank aren't always the same.
Broadheath Bettas · Reference
The Forms:
Few aquarium fish display as much variety as the domestic betta.
Look across a good selection and you may see a compact, athletic Plakat beside a flowing Veiltail, a perfectly rounded Halfmoon, a spiky Crowntail and an extravagantly ruffled Rosetail. They can look so different that it's easy to assume they're separate species. In most cases, they're not.
The colourful ornamental bettas kept in aquaria are nearly all different domesticated forms of the same species, Betta splendens. Their contrasting looks are the result of generations of selective breeding for fin length, tail shape, colour, pattern and body form.
People are usually drawn to a fish by its colour first — which is understandable. But its fin type and overall structure can make a real difference to how it swims, and to the kind of aquarium in which it'll be most comfortable. This guide explains the main forms, how to recognise them, and what their shape means in practice.
First things first
Species, form and colour are three different things
Before the individual types, it helps to separate three terms that often get muddled. Almost every confusing betta name is just a combination of these three.
Species
The biological type of fish. Betta splendens, B. imbellis and B. mahachaiensis are different species.
Fin / body form
Plakat, Halfmoon, Veiltail, Crowntail — these describe the fish's physical shape, mainly its fins. Not separate species.
Colour/pattern
Koi, marble, butterfly, dragon, mustard gas — these describe colour or pattern, not tail shape.
So a single fish can carry several terms at once:
Male · Halfmoon · Koi · Betta splendens
"Halfmoon" is the tail form, "koi" is the pattern, and Betta splendens is the species. Once you can split a name into those three parts, the whole vocabulary stops being intimidating.
The fin & tail forms
The main varieties, one by one
1.
Although modern ornamental Plakats are bred for beauty rather than fighting, they keep that more athletic silhouette. It's also the form closest to the wild Betta splendens — the short-finned body plan is the ancestral one.
Short fins, a compact profile, and a relatively broad tail.
The Plakat's name tells its story. It comes from the Thai pla kat — literally "biting fish".
The short-finned form of the domestic betta is the form closest to the wild fish and to the traditional Siamese fighting strains bred in Thailand for centuries.
The elaborate long-finned varieties came much later, when breeders in the late 1800s and early 1900s first began selecting for beauty rather than combat.
There's a nice linguistic twist, too: in Thailand the short-finned fighter is traditionally called plakat morh, while the long-finned ornamental type is plakat cheen — often rendered as "Chinese fighting fish," a nod to its resemblance to the flowing costumes of Chinese opera.
What they're like to keep
Plakats are generally strong, energetic swimmers. They cope with gentle water movement more comfortably than extremely long-finned fish (though never a powerful current), and their shorter fins are less prone to snagging. So, a healthy Plakat is often an excellent first betta.
Look out for: don't mistake a young long-finned male for a Plakat just because its fins haven't finished growing. Check the proportions of all the fins, and ask the breeder or supplier how the fish was classified.
2.
A long tail that droops and curves downward, giving an asymmetrical outline.
One of the most familiar domestic forms. When the fish is relaxed, the caudal fin hangs like soft fabric; even when it flares, the upper and lower halves don't form a symmetrical circle.
Veiltails were once the standard pet-shop betta and are sometimes overlooked now in favour of newer show forms — but a well-proportioned Veiltail is an elegant, characterful fish.
What they're like to keep
Their fins are longer than a Plakat's, so they appreciate gentle filtration and smooth furnishings — but the finnage is usually less dense and heavily branched than a Rosetail or extreme Halfmoon. A healthy Veiltail makes a very suitable first long-finned betta.
Look out for: a Veiltail's naturally asymmetrical tail shouldn't be mistaken for damage. Torn edges, missing sections or dark, receding margins are different from the normal downward sweep.
3.
What they're like to keep
A Delta has a triangular tail that widens evenly from the base — broad, but short of a full half-circle.
Flared and viewed from the side, the Delta tail resembles the Greek letter: a broad triangle with comparatively straight, symmetrical edges. The Super Delta is a very broad Delta that approaches, but doesn't quite reach, a 180-degree spread.
There's no hard wall between Delta, Super Delta and Halfmoon — they sit along a spectrum of increasing tail spread, and a fish may even appear to spread differently depending on its age, condition and mood.
What they're like to keep
A Delta offers much of the visual impact of a broad tail without the extreme fin area of a full Halfmoon, so — given good body strength and balanced fins — it's a practical and attractive choice. A Super Delta's care is much like a Halfmoon's, with perhaps slightly less fin to carry.
4.
What they're like to keep
A broad, symmetrical caudal fin capable of opening to roughly 180 degrees.
When fully flared, the upper and lower edges of a true Halfmoon form an approximate semicircle, ideally with even ray branching and the outer edges aligning vertically. Its dramatic, balanced outline made it hugely influential in show breeding, and it's now one of the most sought-after ornamental forms.
The Halfmoon is a surprisingly modern creation. The clean 180-degree tail that now defines the "show betta" was only stabilised by breeders in the late 20th century, and it quickly became one of the most influential forms in exhibition circles. Its ideal is set out in the standards of the International Betta Congress, which — notably — judge a show betta as much on health, symmetry and condition as on the spread of its tail.
What they're like to keep
That large tail creates more resistance in the water. A well-bred, healthy Halfmoon still swims confidently, but it benefits from:
✦ gentle filter flow;
✦ resting leaves or broad plants near the surface;
✦ a tank without sharp decorations;
✦ easy access to food;
✦ open space without strong turbulence.
Not every fish sold as a Halfmoon shows a perfect 180-degree spread — some are really Super Deltas, and others only reveal their full spread when displaying.
Look out for: choose a fish with a strong body and fins that look proportionate rather than excessively heavy. A beautiful tail shouldn't stop the fish moving, feeding or surfacing comfortably.
Going Further: Some Halfmoons are bred for even more spread. An Over-Halfmoon opens beyond 180 degrees, the outer rays curving forward past the vertical. It can make a striking show silhouette — but more spread isn't automatically better: push it far enough and the fin area overlaps with Rosetail territory, placing greater demands on the fish. For a home aquarium, balance and swimming ability matter more than the widest possible tail.
5.
Extended fin rays with reduced webbing, creating a spiky, crown-like outline.
The Crowntail is even more recent — it was developed in Indonesia in the 1990s and is now one of the most recognisable of all betta forms. Its spiky look is a matter of genetics as much as appearance: the trait is partially dominant, which is why crossing a Crowntail with an ordinary-finned betta produces the intermediate, comb-edged Combtail in the very first generation, rather than a clean split between the two.
In most fish, a membrane connects the fin rays almost to their tips. In Crowntails, that webbing is reduced, leaving the rays projecting beyond it — a feature that can appear in the caudal, anal and dorsal fins. Breeders distinguish single-ray, double-ray and crossed-ray forms by how the rays are arranged.
A healthy Crowntail isn't inherently more fragile than another betta — but the projecting rays make it especially important to tell normal anatomy from fin damage. Provide clean water, smooth furnishings and gentle filtration.
Look out for: the webbing reduction should be reasonably even. Irregular missing tissue, inflamed edges or progressive shortening point to damage or disease rather than Crowntail form.
Going Further: The Combtail sits between a conventional fin and a full Crowntail: modest ray extensions give a comb-like or lightly serrated edge without the pronounced webbing reduction. This isn't just a loose label — it reflects the genetics. The crowntail trait is partially dominant, so crossing a Crowntail with a normal-finned fish produces an intermediate, comb-edged fish in the very first generation. That's the Combtail.
6.
The caudal fin is divided into a distinct upper and lower lobe.
A Double Tail isn't a normal tail that has torn down the centre — it's a heritable developmental form in which the caudal fin separates into two lobes. Double Tails often have a noticeably broader dorsal fin, and the body may be shorter or more compact.
The Double Tail is one of the clearest examples of a single gene doing a lot of work. The same inherited change that splits the tail into two lobes also broadens the dorsal fin and tends to shorten the body — which is why Double Tails often have that distinctive deep-bodied look, and why careful breeders pay close attention to body shape, not just the tail. Its influence also shows up "hidden" in other lines: pairing Double Tail genetics into single-tailed fish is one way breeders improve dorsal-fin fullness.
What they're like to keep
That large tail creates more resistance in the water. A well-bred, healthy Halfmoon still swims confidently, but it benefits from:
✦ gentle filter flow;
✦ resting leaves or broad plants near the surface;
✦ a tank without sharp decorations;
✦ easy access to food;
✦ open space without strong turbulence.
Look out for: choose a fish with a strong body and fins that look proportionate rather than excessively heavy. A beautiful tail shouldn't stop the fish moving, feeding or surfacing comfortably.
7.
Very heavy fin-ray branching producing overlapping, rose-petal-like folds.
The Rosetail is what happens when the Halfmoon's broad tail is pushed further still — so much extra ray-branching that the fin ruffles and folds like rose petals.
The Feathertail is a yet more extreme expression, where the branching is so heavy that the fin develops pronounced waves and folds.
These fish can be spectacular, especially flaring. But the dense finnage is heavier and more structurally complex than a moderate Halfmoon's.
They are striking examples of selective breeding reaching the edge of what a fin can structurally do: beyond a certain point the extra finnage becomes more decorative than functional, which is exactly why moderate, well-balanced fish are so prized by experienced keepers.
Rosetails generally need very gentle flow, smooth plants and décor, convenient resting places, and close observation of swimming ability. They aren't unhealthy simply because they're Rosetails, but extreme individuals may tire more easily or struggle to carry their fins.
A Welfare Note: here, appearance should never be separated from function. A fish must be able to swim, rest, feed, turn and surface without its fins becoming a serious burden. Selective breeding can produce extraordinary beauty — but responsible breeding also means restraint. For a newer keeper, a Plakat, Veiltail, Delta or moderate Halfmoon is a simpler choice.
8.
✦
✦
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A few forms you'll meet less often, in brief:
Round Tail — a smooth, rounded caudal fin without the downward sweep of a Veiltail or the straight edges of a Delta. Simple and often well-balanced; seen in short-finned fish, females and some longer-finned lines. Don't confuse it with a Halfmoon whose edges have been lost to damage.
Spade Tail — the caudal fin narrows to a central point, like a playing-card spade. Once more commonly recognised, now seen less often and the term used rather loosely. A true example has a deliberate, balanced point rather than an irregularly narrowed tail.
Giant — describes body size, not tail shape. The trait has been mapped to a single major region of the betta genome, and a Giant can carry almost any tail type on its larger frame. A Giant may be a Plakat, Halfmoon or other form, selectively bred for increased growth. They need more room and produce more waste, so shouldn't be kept as ordinary bettas in an undersized tank. "King Betta" is a commercial name used inconsistently — often a large Plakat-type, but not automatically a genetically established Giant.
9.
Female bettas — not a separate fin form
Females are sometimes listed as though "female" were another tail category. It isn't — sex and fin form are separate things. Female Betta splendens usually have shorter fins and smaller bodies than mature long-finned males, but with considerable variation: a female can be Plakat, Crowntail, Halfmoon or Double Tail in background and appearance, and some develop striking colour and impressive finnage. Equally, a young or short-finned male is occasionally mistaken for a female.
The small white ovipositor visible beneath the body can help confirm sex, but it shouldn't be the only feature you rely on.
Which type is best for a first betta?
There's no single form that suits everyone, but some are more forgiving than others. As a rough guide:
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Healthy Plakat
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Veiltail
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Delta
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Moderate Super Delta
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Healthy short-finned female
Easiest First Choices:
Fine with a little extra care:
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Halfmoon
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Crowntail
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Double Tail
Better for the Experienced:
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Extreme Rosetail
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Feathertail
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Over-branched Over-Halfmoon
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Shortened-body fish
Remember that form affects care, but it isn't the whole story. Two Halfmoons can differ greatly — one swims confidently and holds its fins naturally, another is weighed down by excessive branching or poor body structure. And not every Plakat is automatically healthy just because its fins are short.
Whatever the label, look at the actual fish: its swimming strength, body alignment, fin condition, breathing, alertness, appetite, and whether it can rest and surface easily. A label describes the form — it doesn't guarantee quality or health.
For The Curious
How Betta Forms Develop
None of these forms exists in the wild. Every one was created by selective breeding — and the basic idea is simpler than it sounds.
Every generation of fish contains natural variation. A breeder picks the individuals showing a desired feature — a wider tail, shorter fins, stronger red, more ray branching — and breeds from them. If the feature is heritable, some offspring show it too. Repeat this over many generations and the feature becomes more consistent and more pronounced. That's how domestic bettas came to look so far removed from their wild ancestors. Selective breeding doesn't create a trait because the fish "needs" it; it simply changes how common an inherited variant is, because humans choose which fish reproduce.
The Science Behind It
What's remarkable is how few switches are involved. Recent genome studies of hundreds of bettas found that several of the most dramatic features each come down to a single powerful gene. The double tail, the elephant-ear (Dumbo) pectoral fins, and albino colouring are each governed by one major-effect change. Even the defining split between long-finned and short-finned fish traces largely to one region of the genome — and long fins are genetically dominant over short. So the entire spectrum of fancy bettas is, in a sense, a handful of simple switches, combined and recombined in countless ways.
So a short list of heritable traits, mixed together, produces an almost endless catalogue of fish. It's why two ordinary-looking parents can throw a surprising baby, and why the hobby never quite runs out of new combinations to chase.
Why the forms look the way they do
Once you see breeding as "concentrating a trait," the forms start to make intuitive sense.
A Crowntail looks spiky because breeders selected for less webbing between the fin rays — reduce the membrane and the rays stand out like the points of a crown. Push that selection only partway and you get the gentler, comb-edged Combtail in between.
A Rosetail ruffles because the fin rays branch more and more as they're selected for fullness — eventually the fin carries more material than can lie flat, so it folds and overlaps like petals. The Feathertail is that same tendency taken a step further.
A Halfmoon opens to a clean half-circle because generations of breeders selected for ever-greater tail spread, until the edges met at a straight line.
Each "look," in other words, is simply one natural trait dialled up by patient selection.
Domestic bettas and their wild relatives
The domestic Betta splendens population has a complicated history — there has been substantial domestication over many years, with selection and even hybridisation between lineages.
The dazzling variety of the domestic betta isn't the product of grand design — it's what happens when a naturally variable little fish meets centuries of human preference.
A few inherited traits, combined and concentrated, gave us everything from the athletic Plakat to the sweeping Halfmoon.
Knowing how those pieces fit together makes choosing — and appreciating — your betta all the more rewarding. Responsible breeders and keepers aim for fish that are beautiful and healthy — able to swim, feed and behave naturally — rather than chasing an extreme for its own sake. Understanding the forms is part of what makes that possible.
Choose the individual, not just the label
Knowing the forms makes it easier to understand what you're looking at — but classification should never replace observation. A modestly-finned fish with excellent balance, health and character is a better choice than a fashionable specimen that struggles to swim.
Choose the aquarium first, then choose a fish whose form suits that environment and your experience. Every fish we sell is individually photographed, so you can assess the actual specimen — and we're always happy to advise whether a particular betta suits your setup.
New to fishkeeping? Start with the New Fishkeepers Guide. Already have a betta? See the Complete Betta Care Guide.
Scientific Background & Further Reading
For keepers and breeders in the UK
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The Anabantoid Association of Great Britain (AAGB) — the UK society for bettas and related fish, with a members' journal (Labyrinth), articles, show and breeder schemes. A good home for anyone wanting to go deeper or meet other keepers. — aagb.org
For the standards that define the forms
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The International Betta Congress (IBC) — the long-established international body (founded 1963) that writes the exhibition standards defining each form and colour, with health and condition built into the ideal. — ibcbettas.org
For the science behind the forms (open-access)
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Zhang W. et al. (2022), The genetic architecture of phenotypic diversity in the Betta fish. Science Advances 8(38). — the study behind the "few major-effect genes" story.
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Wang L. et al. (2021), Genomic Basis of Striking Fin Shapes and Colors in the Fighting Fish. Molecular Biology and Evolution 38(8). — maps the double-tail, elephant-ear and albino traits to single loci.