If you have both male and female, a pair may form. They must select their mates to be successful, though sometimes this doesn't last either. The two fish in the photo appear to be "friends" so it may be a pair; their interactive behaviour is the best guide to this. If I were to guess at gender, the left appears female and the right male, but I can't be sure. If there is a spawning, be prepared to remove the third fish; not always necessary (to avoid serious damage), but sometimes. Even with lots of cover (plants, chunks of wood, brtanches) it may get picked on relentlessly.
Rams spawn on flat surfaces, or in depressions. Avoid any catfish; these are nocturnal and the eggs/fry are very vulnerable at night when the rams are sleeping. Upper fish such as small peaceful characins (hatchetfish, some pencilfish, some of the tetras) are good dither fish. These are not nocturnal, and during the day the parents have a good chance of protecting the eggs/fry, though sometimes this depends upon the individual rams.
With water parameters, the GH and pH should be close to those in which the parents were raised. This is usually impossible to discern, unless you acquire the fish from a breeder, or they are wild caught. If the latter, it must vbe very soft water with an acidic pH. One important parameter is temperature; this fish needs warmth, so no less than 80F (27C). Obviously, any tankmate species must have similar requirements.
Adding some dried leaves will provide infusoria, the first food for fry, and dried leaves in the tank result in faster growing fry. Oak, beech, maple leaves are safe; you can buy Indian almond leaves in some fish stores. If you collect leaves, they must be completely dead (having fallen off the tree naturally), dry, and free of any toxins (pesticides, oil, chemicals, etc).
Byron.