BETTAS by Jim Sonnier/genetics6

Brilliant Marble Bi-color Plakat (Short Fin) male (fish and photo by Wasan Sattayapun)

In wild type Bettas normal finnage is short somewhat like our domestic females, only a little more angular and pointed. All other finnage types are mutations that affect the original short fins. Some of these mutant genes are inherited as simple dominants, while others appear to be sex influenced or cumulative multiple pairs.

LONG FIN BETTAS are also called Veiltails and they are the kind you find at your local pet store. The male's tail is elongated and droops downward. This type of tail is graceful and beautiful in its own right. This mutation also causes the other fins to be elongated and larger than the normal wild type short fins. The Long Fin mutant is dominant over Short Fin.

DOUBLETAIL BETTAS are produced by another mutant gene that causes the caudal (tail) fin to be divided into two lobes. A secondary characteristic produced by this mutation is a tremendously enlarged dorsal fin. The Doubletail dorsal is many times wider than the dorsal on a Singletail Betta. In fact, the dorsal and anal fins on Doubletail Bettas appear to be about the same size and width. The mutation that causes Doubletail traits in Bettas is recessive to the normal Singletail. Some representative spawning results for the Long Fin and Doubletail genes are presented below...

**Spawnings for Short Fin, Long Fin, and Doubletail**
male parent	female parent	offspring
Short Fin	Long Fin	100% Long Fin (Short Fin genotype)
Short Fin	Long Fin (Short Fin genotype)	50% Long Fin (Short Fin genotype), 50% Short Fin
Long Fin	Doubletail	100% Long Fin (Doubletail genotype)
Long Fin (Doubletail genotype)	Long Fin (Doubletail genotype)	75% Long Fin (67% Doubletail genotype), 25% Doubletail

DELTATAIL BETTAS are a result of selective breeding and have roughly straight edges on each side of their tails. The degree of the tail span can be anywhere from about 120 degrees to near the Half Moon's 180 degrees. It does not appear that any single gene is responsible for this tail shape, but rather a combination of factors, both genetic and environmental. The deltatail shape is one of the most beautiful and durable in Bettas. Even in old age these fish maintain a pleasing and regal appearance.

CROWNTAIL BETTAS appear to have been perfected in the East; Thailand, Singapore, and China. The rays of the fins and tail extend out past the webbing, giving some of these fish a somewhat startling appearance. (note: actually the rays appear to be of normal length and the webbing appears to be reduced) Some fish show rays that extend very far past the webbing - even 50% of the tail length. Some fish show branching that causes a single ray to have 2, 4, 8, or even 16 ray tips. There is even a variety that has crossed rays. Some people say they are outstanding while others say they look more like insects than fish.

HALF MOON BETTAS were created during the last 10 years by European breeders. The most outstanding characteristic of Half Moons is the half circle caudal (tail). The edges are straight - one straight up and the other straight down. The rays and webbing then form a perfect 180 degree half circle around to the forward facing edges. In the ideal Half Moon Betta the dorsal and anal fins are also somewhat modified and together with the caudal all fin edges form a circular pattern approximately two thirds of the way around the body. Another key characteristic of the Half Moons is extra ray branching particularly in the caudal. In normal Bettas the caudal rays branch once, maybe twice in better fish. But in Half Moons the caudal rays branch a third time in the best fish, or even a fourth time . That means a single ray starting from the caudal peduncle can end up with 16 ray ends at the edge of the tail. An important consideration when working with Half Moons is the fact that they do not breed true. From Half Moon parents you may get no Half Moon offspring, or only one or two. Typically you will get less than 10% Half Moon offspring. With careful observation and much hard work these dedicated Betta breeders have created a magnificent new form for all of us to admire and enjoy.

My research and experience with Half Moons leads me to believe that there are at least 3 genetic factors required to produce a Half Moon Betta. First, all caudal rays must be perfectly straight with no curving or bending. Second, the straight caudal rays must branch multiple times with triple branching producing the best fish. Third, extra spread in the webbing between the rays allows the 180 degree caudal fan to form. It appears that the straight rays and the extra webbing spread are heavily impacted by environmental factors. Even if the Betta possesses these genetic traits they may not show because of generally poor water conditions or bad rearing techniques.

If all three of these genetic factors were inherited as recessives (or all three as dominants) then Half Moon Bettas would breed true and you would get 100% Half Moon offspring from a mating of Half Moons. So it seems safe to say that the three genetic factors are a mixture of dominant and recessive traits. My guess would be that the gene for multiple branching is a dominant trait, while the genes for straight rays and extra webbing spread are probably recessive traits. If this hypothesis is correct then only 3 fish out of every 64 offspring from heterogeneous parents would have the required genetic material to become Half Moons, and 2 of those 3 would be heterozygous (not pure) for multiple branching. Then there is the problem of lower quality environmental conditions inhibiting the actions of the Half Moon genes. My overall conclusion is that raising Half Moons is extremely difficult and the numbers of Half Moons produced will quite likely be very small.

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