Mitch is correct - water hyacinth works much better. Lilies do not have enough frilly stuff to catch many eggs. You cannot give the adults the hyacinth too soon though or they will eat all the roots off before spawning time comes around. Since you are spawning them in a cage the netting will also catch some eggs but it will let a lot fall through too. Those that fall to pond bottom will not hatch very well.
Lots of places now cover the bottom of the spawning tank or cage with mat to catch eggs. Something like this:
http://www.aquaticeco.com/index.cfm/...etail/iid/3365
or this:
http://aquaticeco.resultspage.com/se...s=custom&w=pf4
You may find an inexpensive batting in a fabric shop for one-time use. Astroturf and cheap indoor-outdoor carpet works too. Most of this stuff has to be weighted down to keep it from floating or moving about. Don't put the mat in too soon either or it will fill up with muck before spawning time. Even if you use mat, still add some hyacinths because it seems to stimulate spawning and will make it less likely that they blow the eggs out through the sides of the cage. After spawning, the adults are moved back to where they came from and the cage with the eggs attached is moved to a fry pond.
In one of your threads way back when there was a description of the process of developing a zooplankton bloom in the pond. You start with a drained pond and add lawn fertilizer and chicken feed (crumbles, not scratch) as it is being filled. Depending on the temperature and local conditions, there will be plenty of little live things for the fry to eat in one to two weeks. In three to four weeks the plankton will not be much good any more and the predators will have moved in so you have to start the process all over. The obvious problem is that you need to be able to predict when the fish will spawn to make this work.
-steve