Prepare the food cultures:
Getting Bettas to spawn is the easy part: raising the fry is more difficult. Consequently, it is best to begin any breeding program by developing a rich culture of micro-organisms such as "infusoria" and rotifers and a culture of micro-worms and brine shrimp.
"Infusoria" is a term that is used to refer to micro-organisms such as Euglena and Paramecium that grow rapidly when pond water is infused with rotting leaves, such as lettuce or hay straw. Fill a small container with pond water or water siphoned from the bottom of an established aquarium and add a handful of soft lettuce leaves and/or hay straw to it and let it stand for several days. Adding green water from a pond or tank will help the culture develop. As the leaves rot, micro-organisms develop in the water in large numbers, feeding on the decomposing leaves. These can be seen with a low powered microscope- a micro-zoo in a tub
Use a turkey-baster or large eye-dropper to remove the culture to feed to the tiny Betta fry in the first days that they are seen free swimming.
Micro-worms are tiny worms that are easily cultured in a mix of "Easy Oats" or rolled oats mixed with boiled water to a thick, creamy consistency to which a little bakers yeast is added for fermentation.
Prepare the fish for spawning by feeding them well with live foods such as brine shrimp, black worms, blood worms and mosquito larvae. Frozen foods are acceptable for this, too.
When ready to breed, females will be plump and show an egg spot at the vent and males will built a bubble nest at the water surface. The nests may be any size but are usually 5-6 cms across, with the bubbles piled high. Water temperature increases may trigger nest building and water temperature is an important factor, males that show no interest in breeding a water temperature 25oC will do so when the temperature rises to 27-28oC
Adjust the water temperature to the optimum range for breeding, 28oC (82oF), and ensure that the cover plate is in place so that a humid, warm air space exist above the water surface. Betta breeding is also possible within the range 26oC - 30oC (80-86oF) and some breeders have good results at temperatures around 84oF.
Place the male Betta in a wide topped container that is at least 15 cms deep and fitted with a close fitting cover. The water should be well aged and clean and provided with floating plants (Duckweed is suitable) or half of a polystyrene cup cut length wise. If he is ready to breed he will build a bubble nest at the top of the water among the plants or beneath the cup. When he has finished building his nest he will swim just below it and guard it fiercely.
Prepare the fish
Feed both the males and females a balanced diet, including live-foods, to condition then prior to mating. Select males that have begun to build their bubble nests (or wait until the selected specimen does so).
Getting Bettas to spawn presents few problems. Select a "ripe" female Betta, one showing a swollen belly full of eggs, and displaying the brooding stripes that female Bettas develop when ready to breed. If she is ready to lay eggs, a small white spot may be seen at her vent (ovipositor). Place her in with the male.
The male Betta will begin to display and to chase the female and tend to his bubble nest with more intensity. Fights may occur if neither fish is ready to spawn. The whole process can appear very violent.
Sometimes a female will release her eggs prematurely if the male excites her. If this happens then the eggs will not be fertilized so you will have to begin over again with a new female- or wait until the first one is ready again.