Betta (Siamese Fighting Fish) - Reproduction and Early Development

Reproduction and Early Development

Male bettas flare their gills, twist their bodies, and spread their fins if interested in a female. The female will darken in colour, then curve her body back and forth as a response. Males build bubble nests of various sizes and thicknesses at the surface of the water. Plants or rocks that break the surface often form a base for bubble nests. The act of spawning itself is called a "nuptial embrace", for the male wraps his body around the female; around 10–41 eggs are released during each embrace, until the female is exhausted of eggs. The male, in his turn, 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 remain in the male's care. He carefully keeps them in his bubble nest, making sure none fall to the bottom, repairing the bubble nest as needed. Incubation lasts for 24–36 hours; 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. It is common practice in the aquarium hobby to remove the male at this point, so that he would not eat his young (although it has been suggested that this danger is overrated). In this first period of their lives, B. splendens fry are totally dependent on their gills; the labyrinth organ which allows the species to breathe atmospheric oxygen typically develops at 3 to 6 weeks of age, depending on the general growth rate, which can be highly variable. B. splendens can reach sexual maturity at an age as early as 4-5 months.

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. As well as these hybrids within the Betta genus, there have been reports of the inter generic hybridizing of Betta splendens and Macropodus opercularis- the Paradise Fish.