By Joep H. M. van Esch
This article was published in Flare (Journal of the IBC) - March/April 2006, Volume 39, No. 5.

The rosetail is one of the latest tailtype-developments in our beautiful hobby. Opinions differ greatly among breeders whether we should use these fish in our breeding programs or not. In this article I would like to give a short introduction on how the rosetail was developed and how they can be recognized illustrated by several pictures. Please note that this article is based on my personal experiences and thoughts. 


In order to breed and develop the perfect halfmoon betta, betta breeders select their fish on several characteristics like straight rays/edges and multiple branching in order to breed fish which have balanced, well proportioned finnage.


To accomplish this goal and to fixate these characterics breeding methods like inbreeding, linebreeding are often used. The quest for the perfect halfmoon by this breeding method gave rise to a "new" development in the our hobby, the rosetail.

But when did these fish pop-up for the first time? When the CHENMASWIL team was developing the modern halfmoon in the 90s, it was Jeff Wilson who bred the first "mutants". These fish appeared from a cross of his lines with those of Laurent Chenot [1]. Because of their parthership the team regularly exchanged fishes for their HM breeding program they all became familiar with this mutation. Initially they were fascinated by these fish but they appeared to be weaker than the normal fish from the same spawn and failed to spawn. Because of these problems and the fact that they were now producing normal halfmoons of good quality they finally lost interest in these fish. The mutants were never used in their breeding program to develop the halfmoon. Jeff Wilson and Pete Goettner presented some of these fish at the IBC convention around 1993/1994. At this time they described these "mutants" as blonde diamond halfmoons referring to the phenotype of the fish, they were always blonde (pale color) and when not flaring their caudals had the shape of a diamond.

Young copper/gold rosetail (6 weeks old)

Young fish with extreme rosetail signs like the extensive branching in the caudal,  small dorsal and ventral finnage. When you look closely you can already see the asymmetric scaling on the body.


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

Young mustard gas rosetail male [2]

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.


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

Most of the time the rosetail characteristics can be spotted very early in developing youngsters. Especially the extreme forms already show fantastic finnage and impressive spread at a really young age in comparison to their normal siblings. In the beginning this can give great excitement, especially to breeders who are not familiar with this phenomenon, but usually this excitement turns into dissapointment fast after seeing the poor outgrowth of such fish.


Here a comparison of two males which are spawn sibblings. These pictures clearly show the differences between a normal young halfmoon (left) and an young extreme rosetail (right picture).

Young blue mask HM male (8 weeks old)
Young blue mask rosetail HM male (8 weeks old)

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

Copper/gold HM male

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.

Royal blue oHM male [3]

This male is showing a magnificent balanced finnage. The extensive raysplitting and slight overlap points out the presence of rosetail characteristics.

Chocolate/MG rosetail oHM male [4]

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

Metallic blue HM rosetail male [3]

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


Here some examples of rosetail females:

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 [5]

Two extreme rosetail females showing extensive branching in the caudal and small ventrals. Please notice the extremely asymmetric scaling which clearly influences the colordistribution on the body.

Yellow fan- or feathertail HM male [6]

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

Multi color fan- or feathertail HM male [7]

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



Should 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 the normal or moderate sibblings. Others swear by using these fish in their lines and claim that the use of rosetails increases the percentage HM finnage in their lines.
One thing is certain about this, when you use rosetails in your line you will increase the percentage rosetail in the next generation.

To my personal opinion we should be very cautious with this trait. When working with these types of fish you will have to select very strict and strongly in order to keep balanced fish. I personally would prefer to use the normal or moderate sibblings from the rosetail fish for a spawn. Thereby being very carefull in looking for a female with not to much branching in order to compensate the extensive branching.

Blonde blue rosetail HM [3]

Rosetail male with a 230 degree spread and blonde body color. Note the extreme branching and irregular scaling at the body.


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!!


1. Jeff Wilson - United states of America
Bas Schurink - The Netherlands
Marcel van den Bossche (Magicbetta) - Belgium
4. Ilse Hoekstra - The Netherlands


5. Cooleitar - Taiwan
Marion Schultheiss - Germany
Carmen Scharschmidt - Germany

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