The Macropodus fry population seems to be doing well. I have started feeding them brine shrimp, but my production system doesn't produce all that many, and unfortunately I didn't factor in the issue of sustaining production with only a single culture going - soon I will have to start over, and that will result in a 24-hour lag in production.
The fry have grown considerably, but they are still very small. The fry which congregate in the Elodea look like a fruit flies. I have subdivided the fry into several groups (the Elodea group, the open-water group, the heater group) but it's probably more a matter of my perception than it actually is of any subdivision among them.
It's quite interesting to watch the fry hunt brine shrimp. Some of them appear to be more experienced hunters by now - they see the brine shrimp, head straight for them, and gobble them up. Others seem less sure what to do - they see them, follow them for a while, and then pounce. It may be an experience thing - when I first added the brine shrimp all the fry seemed uncertain - they ignored them first, then followed them for a while, and then finally pounced (feeding is always a jerky motion for them).
I'm a little concerned about water quality in the breeding tank. I have had the filter off for over a week now, so both oxygen levels and biofiltration are likely to be lagging. I'm wondering if I should buy a pump and air stone, so that they get the agitation without the intake issues. I suppose I could also find some fine fabric to put over the intake of the filter - switching on the filter would radically alter the fry's world. I also need to think about some other food options - egg yolk, or finely ground fish food - something to supplement brine shrimp (since I really don't have a high-throughput system, or the means to set one up).