Betta splendens

In nature, this specie's males have shorter fins that those we usually see in shops,these are called by the Thai "Plakad" (meaning- "Fighter"), and are used in Thailand for show-fights (just like roosters). Although their fins are short, they are still bigger than those of females. These males are more aggressive than long- finned males, but they are less susceptible to infectious diseases and have faster ability to recover after fights. Of the long-finned strains, there's the most known Veil-tail, which are the commonest in shops. More appreciated tail forms are the Round-tail, Fantail, and Delta-tail. All these tail forms can appear in two fin forms- Double-tail and Comb/ Crown-tail. Double-tail has a long dorsal fin, and their caudal fin is variably divided to two lobes. Comb-tail has fin rays that grow variably longer that the fin's soft tissue, resembling a comb. Crown-tail is a Comb-tail with equal and symmetric lengths of fin rays and soft tissue. Another famous strain and probably the most famous is the Half-moon. This is a fin form, appearing mostly on Delta-tails, in which the caudal fin is spread to 180o, while flaring. Aside of it, the fish must have other criteria to be considered as a true Half-moon. Aside from tail forms, these fish come in all colors and patterns. In nature, they have a black body, with turquoise/blu /steel-blue iridescent on it, and red washes on it fins. The first color strain produced was called Cambodian, with clear-pinkish body and red fins. By today, with further understanding the fish's genetics, we have Solid colored fish, in the colors of Red, Non-red Yellow, Black, White, Orange, Royal-blue, Steel-blue, Turquoise and the newest- Copper. Then comes the Bi-colors, mostly Cambodians and Iridescent with red or yellow washes on their fins. And along side with these, come the Tri-colored, also known as Multi-colored, mainly containing the colors- Clear + Iridescent + Red. Patterns have also developed, from the "solid" regulars, we've got to Variegated-fins (the most appreciated is the known Butterfly), and Marbled (which can change their color patterns throughout their life). Every breeder give different names to the strain lines they create, one of these, most known, is the Mustard-Gas created by Jude Als. By looking at all the colors, patterns and tail and fin forms, it is easy to see why this fish is probably one of the most known and popular freshwater fish all over the world.