Reproduction and nests
The Siamese fighting fish mate in a fashion that is called "nuptial embrace", in which the male and female spiral around each other, around 10-41 eggs are released and fertilized at each embrace, until the female is exhausted of eggs. Once the female has released all of her eggs, she is chased away from the male's territory, as it is likely that she'll eat the eggs due to hunger. The male carefully keeps every egg in his bubble nest, making sure none fall to the bottom, and repairing the bubble nest as needed. Incubation last 24-36 hours, and the eggs hatch in 3-4 days. Bettas live approximately 2-5 years, generally between 2-3, rarely 4-5 years.

Betta males build bubble nests of various sizes and thicknesses at the surface of the water. During and after spawning, the male uses his mouth to retrieve sinking eggs and deposit them in the bubble nest. After approximately two days the eggs hatch, and after three more they become free-swimming fry; The male will insist to keep the fry near the bubble nest in order to keep them alive while their gills develop. Once the fry are older, aggression develops and the fry will leave the bubble nest to find new territories. In captivity, Betta fry are fed infusoria for the first several days, followed by newly hatched brine shrimp or similarly sized food.
B. splendens can be hybridized with B. imbellis, Betta sp. Mahachai and B. smaragdina, though with the latter the fry tend to have low survival rates.

Colors
Bettas have been affectionately nicknamed "The Jewel of the Orient" due to the wide range of colors which are produced through selective breeding.

Wild bettas only exhibit strong colors when agitated. However, breeders have been able to make this coloration permanent, and a wide variety of hues breed true. Bettas come in a variety of colors, such as red, blue, turquoise, orange, yellow, green, or translucent. Most are slightly iridescent, and can appear to change color with different lighting or viewing angle. Breeders have also developed different color patterns such as marble and butterfly, as well as metallic shades such as copper, gold, and opaque.

Breeders around the world continue to develop new varieties. Often, the male species are sold preferentially in stores because of their beauty, compared to the females. Recently, breeders have developed in females the same range of colors previously only bred in males. However, females never develop fins as showy as males of the same type and are almost always more subdued in colouration.

The true albino betta has been feverishly sought after one recorded appearance in 1927, and one in 1953. Neither of them were able to establish a line of true albino betta. In 1994, a hobbyist named Tanaka claims to have successfully bred it.

Tail shapes

Breeders have developed several different tail shapes:

.Veiltail (non-symmetrical tail, only two rays)
.Crowntail (highly frilled, extended spiny rays, also called fringetail)
.Combtail (less extended version of the crown tail)
.Half-moon (large tail fin that forms a 180-degree or larger circle segment)
.Short-finned fighting style (sometimes called "plakat")
.Double-tail (the tail fin is split into two lobes and the dorsal fin is significantly elongated)
.Delta tail (tail span is less than half-moon with sharp edges)
.Fantail (a rounded delta tail)