The Complete Guide to the Rosetail Betta Fish

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By Linh Nguyen Updated on 15 Mar 2023

Aquarists have long been drawn to betta fish for their captivating and vibrant colors. From the graceful Veil Tail to the radiant Combtail, there is an abundance of tail types available for enthusiasts — and one of the most recent additions is the Rosetail (RT). With its unique petal-like appearance and overlapping rays on its caudal fin, this tail type has quickly risen in popularity among breeders.

At first glance, Rosetails can be easily distinguished by their excessive branching and overlapping rays in all three fins. However, have much opinions differ greatly among breeders on whether we should use these fish in our breeding programs or not. So, it is important to understand what goes into creating this unique tail type.

In this blog post, we will provide a brief overview of how Rosetail bettas are developed and how they can be recognized. We will also show several examples to illustrate our points. So keep reading if you want to learn more!

Please note that this article is based on my personal experiences and thoughts.

A Rosetail Betta Fish

A Rosetail Betta Fish

1. What is rosetail betta?

In order to breed and develop the perfect Halfmoon Betta, Betta breeders select their fish based on several characteristics such as straight rays/edges and multiple branching, in order to breed fish that have balanced and well-proportioned finnage.

To accomplish this goal and to fixate on these characteristics, breeding methods such as inbreeding and linebreeding are often used.

The quest for the perfect Halfmoon by this breeding method gave rise to a "new" development in our hobby, the Rosetail.

Nowadays, various degrees of Rosetails, from moderate to extreme forms, can be found. The main characteristic of the Rosetail is excessive branching in all three unpaired fins.

Especially, the excessive branching and overlapping parts in the caudal finnage result in a "rose-like" appearance, which explains the choice of the name. Other characteristics which are often seen with rose tails - especially with the more extreme forms - are smaller ventrals, smaller dorsal, and lighter/paler colored bodies (possibly involving the blonde gene?). In comparison with the normal fish from the same spawn, there is bad/asymmetric scaling, and slower/impaired growth and development. The extensive branching also often influences the swimming capabilities of these types of fish.

Typical appearance of a Rosetail betta fish

Typical appearance of a Rosetail betta fish

2. Origin of Rosetail

In the 1990s, Jeff Wilson of Chenmaswil initiated breeding the initial "mutants" to create a modern Halfmoon. Through cross-breeding his own lines with those of Laurent Chenot's, these fish came into existence and became known as mutated Halfmoons.

The collaboration between the team established an exchange of fish for their HM breeding program, so they all grew to know this mutation well. In the beginning, these peculiar fish piqued their interest. Unfortunately, they appeared weaker than other normal ones from the same spawn and failed to reproduce. Due to these issues combined with Halfmoons of excellent quality now being produced by them, eventually, any enthusiasm dissipated. These mutant specimens were not incorporated into developing the Halfmoon in their reproduction process at all.

At the IBC convention of 1993/1994, Jeff Wilson and Pete Goettner presented some extraordinary fish with remarkable characteristics. Labeled as "blonde Diamond Halfmoons" due to their pale hue and diamond-shaped caudals when not flared, these mutants captivated those in attendance.

Read more about the origin of the Halfmoon betta fish in the article: Halfmoon Betta's Journey To The World.

3. Recognizing a rosetail betta

Usually, the defining traits of a Rosetail can be easily seen in young fish.  Especially, the extreme forms already show fantastic finnage and impressive spread at a really young age compared to their normal siblings. Initially, breeders may be elated when they witness this phenomenon for the first time; however, their enthusiasm often dissipates after seeing the poor outgrowth of such fish.

3.1. Recognizing Rosetail in young fish

Young copper/gold Rosetail (6 weeks old)

Young copper/gold Rosetail (6 weeks old)

Young fish with extreme Rosetail signs like extensive branching in the caudal, small dorsal, and ventral finnage.

Young mustard gas rosetail male

Young mustard gas rosetail male

Young fish with extreme Rosetail signs. Please note the extensive ray splitting in the caudal, dorsal, and anal finnage but also the asymmetric scaling and pale color on the body.

Here we can see a nice comparison of two spawn siblings (8 weeks old) which clearly pointed out the differences between a moderate Rosetail (upper picture) and the extreme form (lower picture).

Young blue mask HM male (8 weeks old)

Young blue mask HM male (8 weeks old)

The fish on the right clearly shows the extreme Rosetail branching, the smaller dorsal, smaller ventrals, and bad scales on the body in comparison with his normal brother. These pictures also clearly show the lighter body color which was described earlier.

3.2. Recognizing Rosetail males

Black Halfmoon Rosetail Betta

Black Halfmoon Rosetail Betta

The caudal finnage of this male is showing mild Rosetail signs. We first see a normal Halfmoon branching but towards the end of the tail, this flows into a more extensive branching at the end.

A Butterfly Halfmoon Betta

A Butterfly Halfmoon Betta

This male is showing a magnificently balanced finnage. The extensive ray splitting and slight overlap point out the presence of Rosetail characteristics.

A Mustard Gas Rosetail Halfmoon Betta

A Mustard Gas Rosetail Halfmoon Betta

This male is showing clear Rosetail characteristics in his caudal finnage (Notice the extensive branching and the rose-like appearance).

A  Rosetail Halfmoon Betta

A Rosetail Halfmoon Betta

This male is an example of a more extreme Rosetail, notice the heavy branching in all three unpaired fins and the lighter-colored body.

Yellow fan- or feathertail HM male

Yellow fan- or feathertail HM male

This male is showing an extreme Rosetail form called fan- or feathertail. The ray splitting in the caudal finnage is built up like a feather. Please note the extensive ray splitting in the dorsal and anal finnage but also the asymmetric scaling on the body.

A Red Dragon Rosetail Halfmoon

A Red Dragon Rosetail Halfmoon

Another example of a male showing the fan- or feathertail finnage. The ray splitting in the caudal finnage is built up like a feather.

3.3. Recognizing Rosetail females

Platinum rosetail female

Platinum rosetail female

Rosetail female is showing clear extensive branching in the caudal and small ventrals. The scaling on the body also is different from what we see in normal fish.

Two extreme rosetail females

Two extreme rosetail females

Two extreme Rosetail females show extensive branching in the caudal and small ventrals. Please notice the extremely asymmetric scaling which clearly influences the color distribution on the body.

4. So, we use rosetails in our lines?

This is a question that each breeder should answer for himself. The opinion about this differs heavily among betta breeders. Some breeders refuse to use these fish and cull the extreme forms. They only use normal or moderate siblings. Others swear by using these fish in their lines and claim that the use of rose tails increases the percentage of HM finnage in their lines.

One thing is certain about this when you use Rosetails in your line you will increase the percentage of Rosetail in the next generation. A breeder using Rosetail bettas in his or her Halfmoon line must be especially wary of excesses - fish that cannot swim normally, or carry the mutant trait known as the “X-Factor Fish” [Poison Fish] - fish with bad scales, short fins, pale color and collapsed fins. When working with these types of fish you will have to select very strictly and strongly in order to keep balanced fish. I personally would prefer to use the normal or moderate siblings from the rose tail fish for a spawn. Thereby very careful in looking for a female with not too much branching in order to compensate for the extensive branching.

Further development of the Rosetail characteristic will maybe lead to the development of a real Fullmoon betta with a 360-degree caudal spread.

But keep in mind a fish has to swim!

An Orange Mustard Gas Rosetail

An Orange Mustard Gas Rosetail

Rosetail male with a 240 degree spread. Note the extreme branching and irregular scaling at the body.

5. Rosetail betta facts

The Rosetail betta fish is a beautiful and unique species of Siamese fighting fish. They have long, flowing fins that are often compared to the shape and texture of rose petals. These fish are sought after by many aquarists due to their unique coloring and finnage.

Here are some of their natural characteristics: 

  • Long, flowing fins with branching or forked tips, give them a ‘Rosetail’ appearance. These tail fins can be up to twice the length of their body and may contain multiple rays, webbing, and an intricate color pattern. 
  • Vibrant colors in shades including blue, red, purple, yellow, white, and black; all typically featuring distinctive iridescent hues.
  • A large head and broad, flat body that can reach up to 3 inches in length.
  • A slender body shape with short but broad dorsal and caudal (tail) fins.
  • Large eyes with a slanted shape, giving them an alert, inquisitive look.
  • A lifespan of up to three years under ideal conditions.

6. Take care Rosetail betta

Rosetail betta fish is considered one of the most exotic types of betta fish breeds due to their attractive colors and distinct finnage. The males have longer fins than the females, making them more popular among hobbyists due to their unique appearance. However, Rosetails are generally more vulnerable to diseases than other types of bettas due to their long fins and relatively weak immune system. so, these fish require an environment that suits their specific needs in order to remain healthy and thrive. 

Here is a quick summary of the requirements needed when caring for this line of betta.


  • The temperature should be between 75 and 82 degrees Fahrenheit. 
  • The pH level of the water should be between 6.0 and 7.5.
  • The hardness of the water should range from 2 to 12 dGH (degrees General Hardness). 
  • Ammonia and nitrite levels must remain at 0 ppm (parts per million). 
  • Perform weekly partial water changes of 30%. 

Habitat: Provide a tank that is between 5 - 10 gallons in size with plenty of hiding places such as rocks, driftwood, or plants for your betta fish to feel safe. 


  • Feed bettas two small meals daily of high-quality betta food. 
  • Provide some variety in the diet with treats such as live or frozen foods like bloodworms, brine shrimp, and mosquito larvae. 
  • Refrain from overfeeding and remove any uneaten food from the tank to prevent water quality issues. 

Tankmates: As they are semi-aggressive, it’s best to keep them in tanks without other aggressive fish like cichlids or gouramis as well as smaller fish that might become food for your betta like guppies or neon tetras. More peaceful tankmates include snails, plecos, small shrimps, and other bottom-dwelling fish. 

Substrate: Soft sand or smooth gravel is best for a Rosetail Betta; sharp substrates can damage their delicate fins. 

Filtration System: The tank should be equipped with an efficient filter system to keep the water clean and free from harmful bacteria that could cause diseases in your betta. 

Plants: A few low-maintenance aquatic plants such as swords and Anubias are ideal for providing shade and oxygenation for your Rosetail Betta. 

Decorations: Driftwood, rocks, and caves provide places of refuge where they can hide when they feel threatened or scared.

Additionally, ensure that your betta fish has access to warm, clean water and a comfortable environment free from stress or diseases by regularly monitoring their health. Lastly, provide plenty of places for them to hide, such as rocks and plants, so they can feel safe and secure in their environment. This will help keep them happy and healthy!


It is clear that the Rosetail betta is a gorgeous fish, and definitely a show-stopper. The branching in all three fins gives it such a unique character, however, their excessive branching can cause some complications, such as difficult swimming and breeding. Breeders of the Rosetail or RT must be careful to not have too much excess as it may cause problems like bad scales, pale coloration, short fins, and collapsed fins. Fish keepers should thoroughly research this type of betta before getting one to ensure that they know exactly what they are signing up for when caring for this fish. Be sure to consider tank size, water parameters, food requirements, and lots of other things when deciding if you're ready to take on a Rosetail betta in your home aquarium. Do you have any experience with RTs? Please let me know in the comment below!


The content of this article is partly based on an article on Rosetail fish by Joep H. M. van Esch, which was published in Flare (Journal of the IBC) - in March/April 2006, Volume 39, No. 5.

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