To complement the many colour strains of Betta splendens, there are also around 12 recognised variations of caudal (tail) fin forms.

As with the Guppy (Poecilia reticulata), Betta splendens carry a diverse range of caudal shapes and in recent years, the size of the caudal has grown much larger. Although still rare, Betta splendens are now beginning to evolve tails as large as 200 degrees. In spite of the variations, all Siamese Fighting Fish caudal fins should have rays evenly distributed above and below the fin centre line. Roundness and fullness are the ideal.

Please note that although there are some strains that produce females with long finnage, this characteristic is not desirable in show lines and should be reserved for the male.

Below is a brief description of the more common Betta splendens tail forms. I would be most grateful for any photographs of these tail forms to brighten up this article and enlighten other readers. If you are willing to donate photographs to Not Catfish! I will of course credit the photographer and provide link if you host a website.

Plakat Thai

Plakat Thai Bettas are the original fighting stock. They have short dorsal and caudal fins and were the first strain developed in Thailand. These are the fish that all long finned Betta splendens originated from and of course have been bred into most of the Betta colour strains. Because of the narrow caudal fin, Plakat Thais' are essentially Half-moon in tail form. Unfortunately, they do not contribute Half-moon genes to long fin Bettas. All that results from a Half-moon / Plakat Thai breeding is Veil Tail fry. Genetically, Plakat Thais' only serve to Plakat Thais', even when bred to long finned Bettas.

Half-Moon

To constitute a true Half-moon the tails must span exactly 180 degrees, with perfectly straight radius, and a nice smooth arc. No exceptions.

This is one reason that a pair of true Half-moons will command silly prices. Half-moons also exhibit extended dorsal, anal, and ventral fins and this is the preferred form. The colour morphs of Half-moon Betta splendens are more limited than other strains but this is developing fast. They have been successfully bred in Steel Blue, Royal Blue, Green, Turquoise, Marble, Butterfly and the latest colours including White Opaques, Red, Orange and Black (Melanos). I believe that the current Half-moon challenge is to breed a Normal Black (Black Lace) or a Yellow strain.

Single Tail

Single Tailed Betta splendens were the first type of Bettas to be developed after the short finned type. Normal Single tailed Bettas, with minimal tail width, are virtually non-existent in shows. This is because Delta and Half-Moon varieties are technically Single-tailed Betta splendens and they are the current trend in todays shows.

Veil Tail

The Veil Tail strain is classed anything with a tail larger than a normal Single Tail, and yet smaller than a Delta Tail. A Veil Tail is the smallest size caudal an aquarist should use when breeding for show quality fish.

Photo Credit Missina Burcaw, Florida, USA.

Photo Credit Missina Burcaw, Florida, USA.

Delta Tail

Delta Tailed Betta splendens have been around at least a decade now. Delta tails are classed as anything larger than a Veil Tail yet smaller than the Half-moon.

Double Tail

Double Tail Bettas possess two distinct caudal lobes, with a complete separation to the base of the caudal peduncle. Overlapping lobes are desired and should always be a factor in any breeders breeding program. They also possess a larger dorsal fin. Additionally, the bodies of Double Tails are more stocky that other Betta splendens.

Breeders should strive to produce Double Tail Bettas with as large lobes as possible and many use Half-moons with Double Tail lines to increase the width of the lobes.

Photo Credit Missina Burcaw, Florida, USA.

Heart Tail

Heart Tail Betta splendens are actually a type of Double Tail. The split of the double tail only occurs at the outer edge of the caudal creating a notch in the tail forming a heart shape. Although this strain is just a "faulty" Double Tail, it is highly sought after. Many people trying to develop this strain end up with true complete Double-tails.

Round Tail

Round Tail Bettas are just as their name implies, Round Tailed. Usually they have smaller tails than the Half-moon variety but are often found in Half-moon spawns.

Triple Tail

This variety has, as its name suggests, three tails. It is quite a rare strain and difficult to develop. It maybe possible to evolve this strain into a strong type by inbreeding and out crossing Double Tails.

Fuse Tail

Again, this is a highly prized rare strain. However, as with the Heart Tail it is also a "faulty" morph .Fuse tail Betta Splendens are actually Double-tails whose caudal lobes are fused together. Because breeders strive for complete splits in Double Tails, the chance of getting Fused Double Tails is low.

Fuse Fin

Fuse Fin Bettas are unique and very rare. Their Dorsal, Caudal, and Anal fins are joined together to form a single fin. Fuse Tail Bettas may hold the key to the evolution of true Fuse Fin Bettas because Fuse Fin Bettas have occasionally shown up in Fuse Tail spawns.