Algae and Aquatic Weed Control
What is Coontail? Identification and How to Get Rid of It
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Last Updated on August 25, 2026 by Adam McBeth
If you’ve pulled a slimy, bushy, dark green strand out of your pond that reminded you of a raccoon’s tail, you’ve probably met coontail. It’s one of the most common submerged weeds in ponds and lakes across the U.S., and while a little of it isn’t a big deal, it can take over a pond fast if the conditions are right. Here’s what it is, why it shows up, and what actually works to control it.
What Coontail Looks Like
Coontail (Ceratophyllum demersum) is a submersed aquatic plant, meaning it grows entirely underwater and doesn’t root into the pond bottom the way most weeds do. It just floats, anchored loosely by fine rhizoids, which is part of why it spreads so easily: a fragment broken off by a boat prop, a rake, or even wind can drift somewhere else and start a brand new colony.
A few ways to tell it apart from other pond weeds:
- Branching, bushy growth that gets denser toward the tips, giving it that raccoon-tail shape the name comes from
- Whorled leaves that grow in rings around the stem, usually 5 to 12 leaves per whorl
- Stiff, forked leaves that feel a little rough or brittle to the touch, unlike the softer leaves of milfoil or elodea
- No roots in the soil – if you pull it up and there’s no root structure attached to the bottom, it’s likely coontail
- Dark olive-green to almost black-green color, especially in older growth
Left: coontail. Right: watermilfoil – note the difference in stem and leaflets.
It’s often confused with watermilfoil or hornwort (which is actually another common name for the same plant), so if you’re not sure what you’re looking at, a photo comparison or a quick call to a local pond management company is worth it before you spend money on the wrong treatment.
Is Coontail Actually Bad for Your Pond?
Not entirely. In moderate amounts, coontail is genuinely useful. It provides cover for baitfish and invertebrates, ducks eat the fruit, and it can help absorb excess nutrients in the water column. Some pond owners intentionally keep a manageable patch of it for exactly these reasons.
Dense coontail growth beneath the pond surface.
The problem is that coontail doesn’t stay moderate for long. In nutrient-rich water (lots of nitrogen and phosphorus from fertilizer runoff, leaf litter, grass clippings, or waterfowl waste), it can form dense mats that:
- Block light from reaching the pond bottom, killing off other beneficial plants
- Choke out swimming, fishing, and boating areas
- Decompose in large volumes and pull oxygen out of the water, which can stress or kill fish
- Clog pump intakes, aeration systems, and fountain components
So the goal usually isn’t total elimination. It’s keeping it in check before it takes over.
Why Coontail Takes Over
Coontail thrives where there’s:
- Excess nutrients feeding rapid growth, most commonly runoff carrying fertilizer or organic debris
- Shallow, sunlit water, since it needs light to grow and shallow areas warm up faster
- Stagnant water with little to no circulation, letting nutrients settle and concentrate near the bottom
That last point matters a lot, because it’s the one most pond owners can actually influence long-term. It’s worth noting, the same conditions that let coontail thrive also feed algae and other unwanted, smelly growth.
How to Control Coontail
Manual and Physical Removal
For small infestations, pulling or raking coontail out by hand (or with a weed rake or underwater cutter) works, at least temporarily. The catch: coontail regrows readily from any fragments left behind, and broken pieces that float away can start new colonies elsewhere in the pond. If you go this route:
- Remove cut material from the water instead of leaving it to decompose and re-release nutrients
- Rake consistently rather than as a one-time cleanup, since regrowth is normal
- Avoid doing this right before or during peak growing season if you can, since it can accelerate fragmentation and spread
Biological Control
Grass carp are a common biological option in larger ponds and lakes, since they’ll graze on submerged vegetation including coontail. A few things to know before going this route:
- Many states require a permit to stock grass carp, and some restrict them entirely, so check your local regulations first
- Sterile (triploid) grass carp are typically required to prevent them from establishing wild populations
- Stocking rate matters. Too few won’t make a dent, too many can strip a pond of all vegetation, including the plants you want to keep
Chemical Control
Aquatic herbicides labeled for submersed weeds can knock back coontail, but this is an area where it’s worth getting it right rather than guessing. Treating too much of a pond at once can trigger a large die-off that depletes oxygen and harms fish, and the correct product and rate depend on your pond’s size, use, and local regulations. If you go this route, we’d recommend working with a licensed aquatic herbicide applicator rather than DIY-ing a large treatment.
Shading the Pond With Pond Dye
One of the lowest-effort, lowest-risk options is non-toxic pond dye. Dye tints the water so sunlight can’t penetrate as deeply, which slows the growth of coontail and other submerged weeds without touching fish, wildlife, or water chemistry. It won’t clear out an existing heavy infestation on its own, but it’s an effective way to help prevent regrowth after you’ve done a manual or chemical treatment, and it’s genuinely easy to maintain. For a full walkthrough on choosing and applying it, see our complete pond dye guide.
Improving Circulation and Aeration
Since stagnant, nutrient-heavy water is what lets coontail explode in the first place, addressing that root cause pays off longer term than any single treatment. A pond or lake fountain or subsurface aerator keeps water moving, adds dissolved oxygen, and helps prevent the nutrient buildup near the bottom that feeds weed growth. It won’t eliminate coontail by itself, but it changes the conditions that let it take over in the first place, which makes every other control method work better and last longer.
In this image here, we can see a newly placed fountain in a pond struggling with algae and coontail overgrowth.
A Realistic Coontail Control Plan
If coontail has taken over a significant part of your pond, a combination approach tends to work best:
- Physically remove the worst of it, or treat it with an appropriately labeled herbicide if the infestation is large
- Add pond dye to limit regrowth by blocking sunlight
- Improve circulation with a fountain or aerator so nutrients don’t keep accumulating near the bottom
- Keep an eye on it through the growing season and do smaller manual removals as needed, rather than waiting for it to become a full mat again
Coontail isn’t a sign anything is seriously wrong with your pond. It’s a sign the pond has more nutrients and stiller water than it can comfortably handle, and it will keep coming back until one of those two things changes.
Not sure whether your pond needs a fountain, an aerator, or both? Our fountain sizing guide walks through it, or you can use our pond calculator to get a recommendation based on your pond’s size.
