Half Moon Betta Fish

What is a Halfmoon Betta Fish and How Big Do They Get?

There are hundreds of different types of betta fish, ranging from Plakats to Samurai to metallic to Mustard Gas to Half Moon and many more. But what do all of these words mean? Are any more valuable than the others? Do they all have specific care requirements?

A Halfmoon betta is a betta that is defined by their tail type. They can come in any coloration or any patterning, including Samurai and Mustard Gas. The Halfmoon is one of the most popular types of bettas, regardless of coloration. The Halfmoon bettas have two main tail types, and despite the fact that their main difference from other bettas is their tail, they do require some special care.

In this article, we will cover the tail type definition, Plakats vs long-tailed halfmoons, deltas, species, care, size, and availability.

Tail Type

The defining tail type of a Half Moon betta is a long, rounded tail that expands to an exact 180 degrees when the fish is upset or showing off. The best way to check the tail rotation of betta is to have it flare. Once flaring, the betta will extend the tail fully, and you can take a picture to determine the degree it expands to.

If the tail extends past 180 degrees, it is called an over half moon, abbreviated OHM. If the tail is less than 180 degrees, the betta will normally be a delta, though depending on the length and expansion, you may also have a veil tail.

Even though other tail types such as crown tails, comb tails, rose tails, and feather tails can have tails that hit 180 degrees, this is often rare, and they are not referred to as half-moon bettas. They are simply referred to as the other identifying tail type.

For example, feather tail bettas have “fluffy” looking tails, and even though they can extend to 180 degrees, the unique tail features override the 180-degree spread.

Plakat vs. Long Tailed Half Moons

Both plakats and long-tailed bettas can have the halfmoon characteristic. A plakat is betta with a very short tail fin, and this name typically only applies to male bettas, as female bettas always have short fins.

In fact, male and female plakat bettas are often confused, as they both have similar fins. Most pet store employees simply label a fish male or female based off of the tail fin length, with no regard to the ventral fins, leading to mistakes.

The best plakat is a half moon plakat. There is not a well-known specific name for a plakat that does not achieve a perfect 180 degrees, but these are much less valuable.

As previously discussed, long finned bettas that are over the 180 degrees are called over half moons, and those under are typically deltas. For the long-finned bettas, it is rare to see them display their full fins unless they are flaring, and they often looked weighed down and uncomfortable, while the plakat’s fins look more even and do not impede their movements.

The deltas and super deltas are not inherently less valuable than the Half Moon betta. The primary aspect that determines the price of a Half Moon or a Delta is the quality of their coloration and overall health.


A delta is a betta fish with a tail spread less than 180 degrees and is not a veil tail, rose tail, comb tail, crown tail, or feather tail. A delta tail can refer to any betta that meets all the variables listed above, but if it is very close to a 180 degree tail spread, it can also be referred to as a super delta. This type of betta is more commonly confused with a Half Moon than any other betta type.


Despite all these different names and types, these bettas are all recognized as the species: Splendens. Betta is a genus with seventy three different species within it. Only a few other species have been domesticated enough to exhibit different tail types, and these options are very limited.

For example, Betta imbellis has been domesticated for a few decades at this point, but you only have two tail options; normal tail or spade tail. The normal tail is similar to that of a low quality plakat, and the spade tail is incredibly similar to this, except it ends in a point.

The coloration is the same for all these fish, with very little differentiation. There is a grading scale based off of the vibrancy of the colors but are not hundreds of different color types to pick form, and we will probably never have a Mustard Gas imbellis.

However, the domesticated betta is not pure splendens but is instead a mix of splendens, imbellis, and smaragdina, at least. All the different colorations and tail types come from the cross between these species and subsequent selective breeding.

Therefore, the pure splendens species also has very limited selection, just like imbellis. The domesticated hybrids are the only ones capable of providing such a wide variety of options, which is what makes them so popular.


Half Moon betta fish have very similar care requirements as other betta fish, but there is a difference between the plakat halfmoon betta and the long fin Half Moon betta.

Just like any other betta, Half Moon betta fish need their water heated between 78 and 82 degrees Fahrenheit. They need a filter and a fully cycled tank, meaning you have enough established bacteria to convert ammonia into nitrates after 24 hours, which takes about a month to achieve.

They also need to be fed a variety of food, with two staple foods and several treat foods, such as frozen brine shrimp, daphnia, blood worms, ants, soldier fly larvae, black worms, white worms, grindal worms, and others.

The primary difference between the two and their care is tank size. Half Moon long finned bettas are often disabled due to the size of their fins. They likely have extreme difficulty getting around and are tend to be less active than their plakat counterparts.

The long finned Half Moon bettas are able to live in a smaller tank, such as a 3 gallon tank, but the plakats are much more active and not dragged down by long fins, so they need at least 5 gallons, with 10 being preferred.


Half Moon bettas tend to be over 2 inches in body length and can reach a little over 3 inches with their tail included. The plakats normally reach a slightly smaller size simply due to their tails, though the bodies can be shorter as well.

This is the average size for splendens but if you happen to get a Half Moon King Betta, they may end up getting a little over 4 inches, as they are a more recent hybrid between splendens and raja, with raja being a larger species.

Despite the long finned bettas achieving a larger size, they can still exist in a smaller space than the plakats. This is comparable to common goldfish needing at least 150 gallons, but the fancy goldfish, which are deformed and slower, only needing 30 gallons.


Luckily, the popularity of this beautiful fish means that it is very available and often cheap, depending on the coloration. Unlike the veil tail, the Half Moon market is not entirely saturated yet, so there is still a good bit of variety and turn over.

While the Half Moon plakats are a bit rarer than the Half Moon long finned bettas, they are still relatively common. However, you should be aware that most of the bettas labeled Half Moons in pet stores are not actually a Half Moon, but rather a Delta, so you should check before buying your fish.

In conclusion, Half Moon betta fish are bettas that have a tail capable of spreading exactly 180 degrees, hence the name “Half Moon”. They come in essentially all colors and in both a short tailed and long tailed form. Their care is very similar to other bettas, with the shorter tailed version requiring a larger living area.

Leave a Comment