The Paradise fish(Macropodus opercularis) is a gourami. As a gourami the males build bubble nests to lay its eggs in. It is one of the earliest pet tropical fish kept by hobbyist. It is quite an easy fish to look after, and breeding paradise fish should not be difficult. It can tolerate a wide range of temperatures and water conditions.
You will need a community tank and a separate raising tank(10 gallons is good) for the young. A heater thermostat. An air driven sponge Filter. A tight fitting glass lid underneath the hood. Duckweed is good for the fish to fix the bubble nest to. A thermometer.
Males can be placed together with females but not other males. Do not put gravel in the raising tank, but keep several plants in plant pots. Either let the fish breed naturally in the community tank or put a healthy male and female into the raising tank, when they are ready to breed.
Lower the water in the raising tank to about 7inches and turn the thermostat to 82F. Then prime the pair with either live food or high protein pellets several times a day. Before too long the female will fatten up with eggs and the male will start building a bubble nest.
It is critical for success in raising the fry that there are no draughts of cold air above the water in the raising tank. The reason is that the fry, being anabantids, will take gulps of air and cold air will harm them. The shallow water helps the young find the surface and helps the male catch eggs to place into the nest.
When the male is ready he will start to build a bubble nest attached to plants or other objects. He may also break off pieces of plants to help anchor the bubble nest. During this process he will guard the nest and drive away other fish including the female. However, once the nest is completed, he will start to try and entice the female to his nest. When the female follows the male to the nest then mating will soon begin.
The male will embrace the female directly underneath the nest and squeeze some eggs out of her simultaneously fertilising them. Both of them are stunned by this for a few seconds. When the male comes to he will start to collect any stray eggs to put into the nest while the female drifts. The eggs float up so most will go directly into the nest. This process is repeated with many embraces and egg fertilisation until the female is spent of eggs.
When spawning has finished, the male starts to guard the nest and take care of the eggs in the nest. It has been known on occasion that the female may help. But mostly he will chase her off. Remove the female at this point. The eggs should hatch in about 4 days with the bubbles drifting apart.
At this point if bred in the community tank then use a shallow bowl and scoop up the bubbles and fry and move them to the raising tank. If bred in the raising tank then remove the male as well.
When the fry have absorbed the yolk sac and become free swimming then start to feed them with infusoria. Do daily 5% water changes to keep the tank clean. After a week or two they will be ready to eat baby brine shrimp and microworms. After a month try crushed dry food as well.
As they young paradise fish grow the males will start to fight with each other and small fish will get bullied so should be separated off.