Ok so I accidentally discovered this. I raise the tiny duckweed plants. So I thought one day why not put this tiny floating plant in the spawning tank. I did it making sure that there was plenty of it under the spawning cup. What I found was that the male was more then happy to still build his nest under the cup with the duckweed there too. As the spawning began I found that the duckweed hair thin roots were helping to hold the eggs in the nest. Less work for the male. When the spawning was finished and I took the female out I found that for the next few days the male had literally little to no work to do as the eggs remained in the nest being held by the roots. In two days when the eggs hatched the fry was able to set or rest on the tiny roots of the duckweed. WOW no babies falling with the male frantically wearing himself out trying to keep them in the nest. This is amazing! Now to continue with the experiment in my next spawn which I just set up this morning I'm planing on taking the male out at the same time I take the female out and see what happens with the eggs and fry. This could be a great discovery for spawning males that like to eat eggs or fry. He can be taken out and you will still have a good batch of fry.Plus saving the male so much back braking work.. Here are a few pictures I've taken of the duckweed in the spawn tank.
Bubble nest, eggs, duckweed.
Newly hatched fry in duckweed
Good idea with the duckweed.. like them not falling down..
My duckweed has a tendency to turn yellow.. it is use to being outside with more sun... maybe the pH might get to it ..
I don't have much to mess with.. since I put netting on top of my daphnia..
I use a flattened cup.. might have to try your idea next season..