Prior to spawning, male Siamese fighting fish build bubble nests of varying sizes at the surface of the water. When a male becomes interested in a female, he will flare his gills, twist his body, and spread his fins. The female darkens in colour and curves her body back and forth. The act of spawning takes place in a "nuptial embrace" where the male wraps his body around the female, each embrace resulting in the release of 10-40 eggs until the female is exhausted of eggs. The male, from his side, releases milt into the water and fertilization takes place externally. During and after spawning, the male uses his mouth to retrieve sinking eggs and deposit them in the bubble nest (during mating the female sometimes assists her partner, but more often she will simply devour all the eggs that she manages to catch). 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 eggs then remain in the male's care. He keeps them in the bubble nest, making sure none fall to the bottom and repairing the nest as needed. Incubation lasts for 24–36 hours, and the newly hatched larvae remain in the nest for the next 2–3 days, until their yolk sacs are fully absorbed. Afterwards the fry leave the nest and the free-swimming stage begins.