Firstly, I always keep my breeding stock sexually segregated, males in one tank, females in another, and condition them seperately. I find that the females become better conditioned that way, if there are males around, they tend to be harassed a little and often drop a few eggs from time to time. Keeping them quiet gives a very full, very receptive female.
Secondly, I'd add some frozen bloodworm to their diet. Freeze dried stuff is okay, but frozen is better. If you have a source of safe live food, I'd be giving that as well.
A well conditioned pair will frequently begin to spawn within a few hours of being introduced to a breeding tank if they have been kept apart. If not, then you need to trick them!
Most, (all that I have dealt with - probably all generally), of the small Rasbora a seasonal breeders. They begin breeding at the onset of the rainy season, (in the wild of course). So what you need to do is consider what this means. Large quantites of pretty much distilled water suddenly start falling on the habitat. Obvious effects are, dilution of mineral/pollutant content, drop in temperature, and flooding to a shallow depth, areas which were previously exposed. Perhaps now you can see the logic behind stories of reducing pH, temperature and water level!
Once you've got them to spawn, take them out as they'll hunt down and eat the eggs. Water conditions are very important - the fish may well spawn, but the eggs won't hatch if the water is anything other than soft. The Ca++ ions react with the egg shell and make it impossibly for the fry to break out.
Specifics...
1) I think I've covered that already to a certain extent. My stock fish are held at pH 6.5 - 7.0 and breeding tank somewhere between 6.2 and 6.7, i.e. slightly lower. That change does not stress the fish, it is part of the stimuli.
2) No idea - always used real ones - sorry. Can't see why not - but then, I'm not a Rasbora.
3) Again - covered to a certain extent. The fish move into water areas that are flooded to a shallow depth because the larger predatory fish cannot follow them. My breeding tank is usually only 150mm - 200mm deep. I don't drop it further, but can see valid reasons for doing so, just don't go mad.
4) R. heteromorpha eggs are small, because the fish is small, but actually larger than many egg scatterers that lay 1000's of minute eggs. The reason you get conflicting stories is because we are not dealing with machines. In every batch of fry there will be larger ones and smaller ones. In every batch of brine shrimp nauplii there will be bigger ones and smaller ones. With a small fry species, even the big ones can't eat the smallest nauplii, so infusoria is required. In a borderline case like this, there will be enough larger fry and smaller nauplii to get some results. You will always get better results if you feed basically small fry with a mixture. Of course, if, (as I stongly recommend), you have two very well matured sponge filters in the breeding tank, their surface becomes covered with phytoplankton/rotifers etc., and you'll see the fry congregate around the sponges for that reason.
I could go on - but this is already turning into a book!
I have yet to see any spawning activity although I do have some wide-leaved plants in the community tank.
