So, I did it; I finally decided that I needed to scoop my quartet into a manageable space. However, I didn't want to take them out of the spawn/grow out tank and risk shock. Daddy's still not predatory and the four are growing well, but I wanted to respawn with Wild Card in the hopes that they'd embrace better after their first time together and produce a larger spawn. However, they're on their second week, and big enough to dart over and snack on newly hatched fry. So the first spawn needs to be contained, but without subjecting them to shock or cutting off their water flow by simple cupping. What to do?
I present the DIY for how to gather small amounts of fry into one easily feedable spot in a tank while allowing water flow:
--Take half a 2 liter soda bottle and with any sort of sharp object smaller than your spawn (I used a large gauge needle) put in plenty of holes all around. Don't put them on the bottom; this will allow you to feed them and easily suction up the remnants afterwards.
--Take four large foam circles from a hair curler set. Cut them so that they rest halfway onto the edges of the soda bottle. Take fishing line and loop through one of your small holes, tying a knot in the middle of each piece of foam to secure it.
Tada! That's it! Now the four are secured where water can continue to flow in and out, but they are easy to find and feed, and if you want to redo a pairing in hopes of a larger spawn (which I am), you can prevent sibling predation without risking shocking the small fry by moving them to a different tank/cupping them. Picture below. All four are inside and happily snacking on infusoria. Dad wasn't particularly thrilled about this, but seems resigned to the situation. He can still see and smell his fry, which is enough to not continue his stress.
(I took this picture the right way around, but the forum decided to turn it on its side...)