How Do Betta Fish Mate?

Betta fish are a beautiful and feisty breed of fish endemic to Thailand and are one of the most popular freshwater aquarium fish. The betta mating process is fascinating to watch, and they will breed quite readily if their tank conditions are perfect. However, you might ask how exactly these spirited fish reproduce?

Betta fish mate by engaging in a courtship ritual that ends in a nuptial clasp. The male holds the female upside-down to position their genital pores releasing eggs and sperm. The male builds a bubble nest before mating, catches all the eggs the female releases and tends them in the nest. 

The mating ritual of the betta fish is quite elaborate, and if you are lucky enough to have a pair ready to breed, it can be quite a beautiful process to behold. Please read on to get all the information you need on how these fighter fish sexually reproduce.

Preparation For Mating 

Dedending on their environment, the betta fish typically reaches sexual maturity between the ages of 3 to 12 months, and they will be ready to reproduce.

Young bettas are sexually distinguished until about three months of age, when the male betta develops brighter colors and their characteristic longer fin shape. At this stage of sexual development, male bettas tend to start displaying aggressive behavior to other males in the tank.

Blue Betta

Readiness For Spawning 

During the pre-spawning period, the bettas communicate their sexual readiness by adapting their colors. The male colors become more brilliant throughout its body as females tend to be attracted to the more brightly colored potential mates.

The female betta displays her receptivity for mating by developing markings of two to three darker horizontal bands known as ‘breeding bars.’ The female’s egg tube should be evident as a small white spot on her abdomen.

Bubble Nest

When a male betta is ready to mate, they tend to exhibit more intensified territorial behavior if housed in a tank with other males. The male will also display a more vivid ‘nuptial coloration’ and begin to build a bubble nest.

The male signifies his readiness to mate by building his nest by blowing out bubbles one at a time and taking the bubble into his mouth and lining it with mucus. The betta then deposits these bubbles on the water’s surface to form a floating mass of mucus-coated bubbles.

Typically the betta will create his nest around floating plant material or the sides or corners of the aquarium space at around 6cm.

Betta Fish Mating Ritual

Mating Dance

After the male has built his nest and the female has signaled her receptivity, the male leads the female towards the nest by presenting lateral and frontal displays. He approaches slowly and undulates his caudal region and fin.

This dance of the male betta also involves gill erection with lateral and frontal displays, and the male may engage in butting and chasing actions if the female does not approach the bubble nest willingly.

The male will then adopt a curved body position while circling the female as she tilts her body upwards to the male in his U-shaped presentation position. When the fish have adjusted to the appropriate position, the male enfolds the female so that his head and caudal fin are almost touching.

Mating Clasp

This ‘clasp’ brings the genital pores, and the female bends her body into a sigmoid curve where the male tightens his clasp. They then enter the quiver and roll stage, where the female is placed in an upside-down position with her urogenital pore close to the nest.

Egg release usually coincides with this rolling activity, and the pair will often sink slowly during the nuptial clasp. The female releases her unfertilized eggs into the water while the male releases his sperm which fertilizes the eggs that fall through this ‘milt.’

They then loosen from the clasp, and they may appear motionless for several seconds. They will repeat this process until the female betta releases all its eggs.

Here is a short but stunning video that shows two bettas in the nuptial clasp if you would like to view their beautiful dance:

Post-Spawning Egg Collection

The released eggs slowly sink to the bottom of the tank and are typically caught by the curved body of the male. The male takes the eggs in his mouth and places them in the bubble nest while the female swims downwards to retrieve the lost eggs from the substrate (often unsuccessfully.)

Once all the eggs are deposited, the male usually stands guard beneath the nest while the female avoids the nest area. The male may become aggressive towards the female at this stage as the female may eat the eggs after spawning. It would be best to remove the female from the tank at this stage.

Caring For the Eggs

The male betta is a great dad and takes over all the care of his developing eggs. Although the male might appear to eat an egg or two, these are usually unfertilized eggs that have begun to decay.

He conducts repairs to his nest and ensures that none of the eggs fall from the bubble nest. Each brood is an average of 40 fry, although the numbers may be substantially higher.

Incubation lasts around 24 to 36 hours, but the newly hatched bettas will stay under the male betta’s care for 2 to three days until their egg sacs are fully absorbed.

The fry is then ready to start their own lives, where they will reach sexual maturity between 4 to 5 months, depending on their environment.

Closing Thoughts

If you have the perfect tank conditions, bettas are easy to breed, and you will experience the betta mating process in real life. The elaborate rituals are somewhat like a romance movie, with the female swooning and the dashing males holding the female in a passionate embrace!

Ensure that you remove the female after their nuptials are complete, lest your romance turns into a horror movie!