A simple net enclosure sufficed and after the fish had spat out the last of the fry I returned it to the community.
For the next week I watched the unenclosed fry. At first the adult chocolates rushed up to the fry and stopped. Only one look and the adults lost interest in the fry completely. So I simply upended the enclosure and released the fry.
One can see exactly the same behaviour in the mouth brooding Bettas such as albimarginata. There is an instinct not to eat the fry.
For the first two weeks the fry stay in the floating plants close to the surface. The photo below was taken when I first noticed the fry on the surface. The Riccia is 1mm wide by the way.
Newly hatched brine shrimp were fed for the first few days. Brine shrimp swim towards light so at least some are at the surface where the fry are. The adult chocolates below happily ate the shrimp that fell into deeper water.
Micro-worms were fed a few times but these fall quickly away from the surface and out of reach of the fry.
After two weeks the fry began to venture into deeper water and would follow the shrimp as it fell; the adult chocolates ignore them. So brine shrimp is now alternated with micro-worms.
So unless there is a reason, I wouldn't recommend stressing everyone out by trying to separate the brooder. One can perhaps use a ladle to transfer fry for separate upbringing if one wishes.
Like the mouth brooding Bettas, the brooding chocolate needs some time away from the other fish to recover from the two-week fast otherwise they will mate again in about a week. To carry a second batch of eggs for two weeks in so short a time takes a toll and there is a visible weight loss. This is not really what we would expect to be female behaviour,
However, if the brooder is male then it makes sense because the female would have had three weeks to recover after laying 50 or more quite large eggs.
From observation of a number of spawnings as they happen, I am well aware of who lays the eggs and who broods the fry.
In time, I hope to take video footage that clearly shows the complete spawning, and settle the question of maternal vs paternal mouth-brooding.
With the first few spawnings, the fish would not eat for the first few days and then resumed eating after the fourth day.
To me this indicates that the eggs have died.
As the fish continued to spawn every four weeks with the same result, I paid more attention to the water quality and also lowered the pH to below 5. Then brooding extended past the fourth day mark.
Two possible reasons for the failures come to mind.
Firstly, The presence of carbonate hardness. With some Parosphromenus species it has been found that eggs do not hatch in the presence of carbonate hardness. (Source: The Parosphromenus Project website.) This could be the same with chocolates.
Secondly, the bacterial count in the water was perhaps too high. Possibly because the pH was allowed to rise towards 6.
So water was changed more often to keep pH below 5, and the cleaning of debris from the aquarium floor was done more often. Then the chocolates began to brood past the fourth day.
My presumption is that the first four days while the eggs are developing is the critical period when you have to pay attention to water quality.
Next: What to do when the fourteen day brooding period draws towards a close and fry are expected.