Depends on how shallow, I guess. My fish spawn literally all over the pond, deep end and shallow end, all along the edges, on anything and everything they can find. They prefer plant matter, but I have used the mop heads you're speaking of with some success. One will probably not be sufficient, though.

Ponds with rocks are the most difficult to eliminate fish babies because the eggs get sprayed between them so the koi can't reach them to eat them. A bare liner pond will make it easer for the fish to find the eggs. I have coping stones around the top of my pond, so after the fish have spawned, I lower the water level at least six inches, exposing the coping stones to the air. I leave the level down overnight, allowing the eggs to dry out. I also remove all the plants and allow them to dry out overnight. The next morning, I return them to the pond and fill it back up.

Also, don't feed the fish for a few days. This forces them to forage on the remaining eggs.

As a last measure, after four or five days, when the eggs begin to hatch, I attach a very strong garden sprayer to the garden hose, and I spray forcefully along the edges and in and around the coping stones. I also reach into the pond and spray along the sides (in the water) where the baby fish attach themselves immediately after hatching. They're still very small and very delicate, and the harsh spray will kill them. I've been doing this for three years and have not had a single surviving baby during this time.

Oh, forgot. You can let the mop heads float. The fish will come almost completely out of the water to get their eggs onto a surface that they like.

Troy,
Get yourself a half dozen Golden Orfes and you won't have any babies. I have had Golden Orfes for the last twenty years and in that time not one baby has ever made it in the pond with the Orfes. Yes they have made in the filter and a connected pond. There are goldfish, koi and golden orfes in this pond and every year they breed like crazy and I never do anything but let the orfes do their thing.
Mike

Don't golden orfes get large in the pond? What about them breeding and then having the same issue with them?

Troy

Troy,
Yes they can get to be 20 inches long and weigh about two pounds. If that is large then they get large. They eat all babies and only babies. That includes their own. Once a fish gets to be about 2" long they won't eat it.
Mike

I have raised Orfe for several years also with the same experience as Mike. They do require a larger pond than goldfish and prefer to spawn in streams. What a great pond fish.

i've heard others speak highly of Orfes, both as an ornamental pond fish and for population control, but they seem a little hard to find in this part of the country, and I'm overstocked as it is. However, if I ever have room, I'll probably try to locate a few of them.

I have 4 Orfes and the largest one is the size of a medium size trout. Every year she gets into my Savio skimmer and drops what looks like 3,000 eggs. What a mess but I love them. They will beat any fish you have to the food first. Very fast and like to dart around. They also LOVE grubs. I do a lot of landscaping around my house and carry a cup around with me when I am digging. I collect any grubs I find and toss them one at a time in the pond. They practically eat them before they hit the water. It's a real enjoyment to watch.

-Mike