Betta Fish Mating
To begin introducing the Bettas, before the Betta fish mating process starts, put the two fish in separate tanks where they can watch the other, but cannot intermingle. You should do this for approximately 4-10 days.
Then prepare the ten gallon mating tank. It is preferable to use an empty tank with a few plants but no pebbles on the bottom. The necessary temperature is about 75-80 F, so depending on the conditions in your home, you may need to buy a small water heater. You'll also require a water oxygenator. An oxygenator keeps the water clean and is better for the fries than a water filter. Half a foot of water in the mating tank is enough - keep it shallow. The male Betta will create a bubble nest before - arranging a large leaf or piece of foam in the tank will assist him.
When the male and female meet, the male will wind his body, flare his gills, and spread his fins if he's excited. The male will begin building a bubble nest in the first 48 hours after swimming with the female. If he hasn't started making the bubble nest for three days, separate the male and female and give it another try, starting with giving them high quality foods again.
The actual Betta fish breeding will look like the male embracing his entire body around the female (called the embrace). Each embrace will result in ten to forty eggs until the female is out of eggs. When the female Betta is out of eggs, the male will sieze his territory and not let her near (otherwise she'll consume the fertilized eggs out of hunger). Once the eggs are fertilized and safely on the bubble nest near the top of the fish tank, the male will keep to catch dropping eggs and return them back to the bubble nest.
The male will continue repeating this for the next 48 hours. After 48 hours, you will see the first of the babies! As a final precaution, 48 hours after the fries are born, separate the male Betta fish so he does not eat his young. Congrats on the successful mating of your Bettas. Take great care of all the baby Bettas!