We have seen some smaller, likely Abdopus animals from Indonesia and most are nocturnal and arrive as adults. I don't recall any successful hatchlings but these are what are termed small egg animals and sadly, won't survive. We think a major key to tank survival of small egg animals (which include the common, Vulgaris, octopus) is predicated on proper food in the water column. Our best guess is that this needs to include new hatched crab as the only (and still very limited) successes have been when crab zoea were presented.
Please DO continue to document what you are feeding, your environment and the lifespan you are able to accomplish. I believe our 2 longest success on TONMO were slightly more than 20 days.
For food I have live Tiger Pods and these frozen cubes. I think the tiger pods might be a bit large for them.
I lost a lot of the first hatch by today. I changed the water today. It looked a bit yellow from the frozen food - I put in a full cube, probably too much. I transferred ~7 live babies to the new water. Same set up in the 5 gallon bucket. Within a few hours there are at lest 20+ babies. Some more must be hatching.
Attached is a picture of my dirty glass on my display tank. As you can see there are plenty of copepods, large and very small. I wonder if my best bet is to just put them back in the main tank and hope for the best.
If you can, you might try replacing any water you change with the water from the original tank and not new water. There is anecdotal evidence that this might make a bit of difference because mass dieoffs appear to occur right after a water change.
Update is I am pretty sure there are no survivors. I didn't see any of the fry eating anything (I was looking under magnification). Mortality rate was fast ~12-24 hours. It was hard to keep track because they kept hatching in waves. Once I separated a batch of ~30-50 and they had all died within a day doing everything I could I figured continued effort was futile. Everything was put back into the main tank. I have not really cleaned the glass and looked around at night to see if there are any survivors.