Probably popularized in the USA by Gary Greenwood of Wisconsin, variations of this technique have been used in Europe for some time. The simple description is to pack a tank with sphagnum peat moss or a variation of Java Moss and allow the parent fish to reproduce until fry are seen swimming at the surface and then remove the parents.
Many of the more difficult Aphyosemion species can be successfully bred with this technique. Diapterons and some of the more sensitive members of Mesoaphyosemions such as A. joergenscheel and A. mimbon are often successful using the style.
More specifically, the popular technique is to obtain “Mossy Be” fiber sphagnum which is a good size as it is packaged. The sphagnum should be placed in a large container filled with water and allow for it to become saturated. Sterilization can be achieved by boiling the peat, but I have used it direct from the packaging after it becomes water-logged.
I have found a ten-gallon tank is a good size to work with, although I have used 5-gallon tanks. Simply submerge the sphagnum into the tank until it fills the majority of the space. I use sponge filters in my tanks. A pair or two can be placed into the tank to start the breeding process. After two weeks I begin searching for fry. Once the first fry appear, I then move the parents to another tank and allow them to breed there.
The fry are left in the original tank to grow out. The smaller ones need infusoria to get a start, but the sphagnum and any floating plants will provide some of this. Infusoria can also be cultivated (see live foods and feeding) and shortly, baby brine shrimp can become a stable food. I have found Diapterons particularly like daphnia as adults and the introduction of daphnia into the baby tank provides another source of food since daphnia release tiny naupali also. Because Daphnia are filter feeders, they also help keep the water clean. A few ramshorn snail also provide cleaner conditions by eating left-over food and stimulating infusoria growth.
Some fry grow a bit on the slow side, but 6-8 months should be sexing out.