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Pond Duckweed!!

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There is a pond behind my house that used to be decent for fishing. Lately since there is no water flow duckweed and lily pads have taken over and it looks terrible. Is there a chance there are fish under this stuff? Also how would you get rid of it?

Thick duckweed can easily shade out phytoplankton, the main base of a bass food chain. Add some thick leaved lily pads and the situation is worse. DO actually drops even with tons of vegetation since there is very little if any mixing of surface vegetation into the water below.

If the pond is yours, consider spreading black visquine over the duckweed long enough to shade it out, taking a few weeks. You can also surface dredge it using a long narrow section of net, pulling it to one side and physically scooping it out. Tough job. I'd kill as much as possible. BEFORE it comes back up next spring add fertilizer to the pond to grow plankton, reducing sun penetration. Feed the phytoplankton as often as needed. Be sure to get the water analyzed before investing in all that. Your NRCS agent can do that, so could a DNR biologist if willing. He might recommend rennovating the pond by draining and following a management plan.

Jim

  • Super User

I know nothing about that pond, but I do know that both duckweed and lily pads can be excellent fish-holding cover.

For lily pads, I would fish topwaters, and soft plastics, retrieving these over, around and through the pads, letting them sink into holes and at the edges.

For duckweed, fish weedless topwaters, slowly and erratically, or steady and fast, whatever seems to do the trick. Regardless, have a rod at the ready rigged with a soft plastic. If a fish blows up and misses the lure, toss that soft plastic as quickly as possible into the hole just created by the blowup.

Most of my experience with duckweed and lily pads has been in lakes. Things could be completely different in a small pond that has been taken over by these plants.

I agree duckweed (and lily pads) is likely to be an asset on a larger fishery like a lake, and even on a slow moving bayou. That type of cover, in moderation, is fine on a well managed pond with some deep water somewhere in it as well as a way to keep oxygenated water in it. It wouldn't likely completely take over since it needs mostly a soft bottom that gets awakened every spring by sunlight. It wouldn't take over in deep water or hard bottoms.

It's best to have a spillway to allow excess duckweed to exit, which also requires a water replenishment source. From time to time surface water can be drained, but that removes the richest water containing most nutrients. Bottom water is what ought to be drained out occasionally.

Two or three consecutive years of re-emerging duckweed can ruin a pond after first seeing the fish become stunted, causing all the fish to die due to starvation or oxygen depletion. Fish that can gulp air are unable to do that because of the duckweed interfering. I saw huge problems with duckweed in very shallowest (no flow) wetland areas where pond levees trapped surface water but it wasn't practical to deal with the stuff. Fishermen came by the hundreds expecting to do well in very fishy looking places, but about all they found around water was insects, frogs and snakes no matter how many fish were stocked. The prime objective was water retention, restoration of wetlands, but our second motive was establishing and managing wildlife resources. Once duckweed takes over most wildlife departs without spending mega dollars managing it. The best we could do was manage for migratory birds like ducks with help from duck-loving volunteers monitoring areas for the need of draining or pumping water in.

Jim

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