Hornwart Stats
Care Level: Very easy
Water Conditions : 6-7.5 pH, Soft to Very Hard
Lighting: Low to high
Maximum Size: 2-6 feet
Introduction
Hornwort (Ceratophyllum demersum), also known as Coontail, is a fast growing, aquatic flowering plant. It is commonly found in marshes, streams and lakes in North American and has been naturalized in parts of Europe. Many other regions – most notably Tasmania, consider hornwort an invasive species, and prohibit the possession or transportation of it.
Hornwort is easily one of the most popular aquarium plants and can be found in nearly any store that sells fish. It can adapt to almost any water type, and can tolerate a wide extreme of temperatures.
Because of its fast growing nature, many people use this plant to soak up nitrates in breeding tanks, or provide safe hiding places for fry in community fish tanks. When hornwort is allowed to float at the top of a fish tank, it provides a perfect refuge for tiny fry from hungry adult fish.
It it also often used in newly established fish tanks, or fish tanks with water quality problems. The fast growing plant will help balance out the water quality, and numerous fish tank crashes have been avoided by adding a large bunch of hornwort when there is an ammonia spike in an aquarium.
It should be mentioned that this plant is rarely used in showcase or highly visible fish tanks. It grows so quickly that it is difficult to aquascape with, and when planted, it has the unfortunate side effect of shedding needles like an old Christmas tree in the aquarium.
Care
Hornwort thrives in a wide range of temperatures and in almost any lighting. Lighting should be kept on the low to medium side, and limited to about 8 hours a day. Any more than this, and the hornwort will take on a long stringy form, with large unsightly gaps between the needles.
It can be planted or allowed to float freely, but when planted the lower sections of the plant will often die. It does form a root like structure when placed in the substrate, but quickly starts to look terrible as it loses needles near the base of the plant. Because of this, it’s often easier to just let the plant float in the tank, and avoid planting it in the substrate all together.
Propagation
Hornwort is incredibly easy to propagate. It will naturally grow side shoots off the main stem, and these can be pinched off to grow another full plant. Sections of the main stem can also be broken off, and both pieces will grow into full plants.
Compatibility
Hornwort is compatible with all fish, and is one of the few plants that will survive in a goldfish tank. That’s not to say that the goldfish won’t nibble on the plant, but it’s spiky nature and phenomenal growth rate, ensures that it will survive in a goldfish tank – as long as they aren’t too hungry.
It is also an excellent plant to have in live-bearer tanks, and as stated before – is a great refuge for baby fish. It provides a food source for the small fish (infusoria living on the plant needles), and the spiky needles generally keep the adult fish away from the baby fish.
Thank you for this article. It was very informative. I will be adding hornwort to most of my tanks!
That’s good to hear. It’s a great plant, and fun to grow.
It is VERY easy to grow. I just got into planted tanks and threw it in all my tanks. Already it is growing 2-3 inches a day. Can be tied to decorations, let it float around on it’s own, or just plant any part of it.
The only downside to this plant, is when it starts to shed needles. Otherwise its great, and it really helps keep the water exceptionally clean with its fast growth and ability to suck up nutrients. I always keep hornwort going in a few of my tanks, and have large bundles in my breeding tanks.
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Hi,,,we need to plant them in Gravel or i will Grow just by floating ….I have two pieces or Ceratophyllum(Hornwort) and i need to make many for breeding my moli ….pls help me in producing more Hornwort
They tend to grow much better floating, as long as there isn’t too much current. When they’re plants, the bottom of the plants often shed needles, and don’t grow as well in my experience. But if you keep them floating in relatively still water, with good lighting, you should have more growth than you know what to do with soon.
I just got some last week and I have it planted. Mine has flowers on it. 1 flower opens every other day or so and is only open for 1 day. Is this common? It’s also growing like super fast. My other ones (same kind) aren’t growing as fast as this one.
They are pretty common on hornwort, and hornwort grows like a weed. I usually only use it in immature aquariums, as it becomes too much of a pain to control after a while.
What does it mean when chunks break off ? I’very had mine about a month and it’s growing like the proverbial weed and portions of it are breaking off. I’ve been replanting it along. Is this normal. Thanks, Rod.
It’s completely normal, and one of the reasons this plant can be a pain to keep. It often breaks off, and sheds many of its needles, which results in a lot of cleanup in the tank.
In nursery tanks, or the new tanks I keep it in, I usually just allow it to float free, which is easier to deal with.
Planning on putting some in my 44 Gallon Pentagon – it has a fast current on top will that cause problems if I float it?
You might run into some problems, since there is so little surface area. It will most likely tumble a lot, and loss fair bit of its needles. It might be best to try and anchor it lower, though that would probably give you some issues as well. It tends to rot when anchored and has to be re-anchored regularly.
In the past, when I had to keep a plant in a tank like this with a lot of current, I would put invisible tubing across the top so it would catch on it, and not constantly circle the top of the tank. It’s something to consider.
Hey Rob keep up the awesome work. I was wondering if you could do a page on hair grass. It would be much appreciated. Ethan
Thanks, Ethan. I always appreciate the feedback. And I’ll add hair grass to the list.
My hornwort had soft small needles when I bought it, with very short internodes. Now in my tank it’s grown huge brittle needles with wider internodes. Have I given it too much light? I can’t dim my aquarium lights or turn one off so I’m unsure how I could reduce light. The only thing I think I could do is attach the hornwort to the side of the tank and lower it down to about halfway (it’s floating at the surface at the moment).
There’s not much to do in this situation, and it’s why many people only use hornwort when they’re establishing at tank. Between shedding needles and stringy growth under high light, it’s too difficult to aquascape with. It’s great in new tanks, because its fast growth helps to keep any sudden ammonia spikes at bay. But once a tank is mature, most people remove it.
The one thing you could try is to actually plant it in the substrate near other plants, and competing for light may reduce its growth. It’s the only thing I can think of to improve its growth right now.
Are the needles dangerous to Goldfish? I have a bucket pond with simple setup for hydroponics. The water filters through the plants and vermiculite, trickling down into the bucket pond. I’ve noticed since adding the hornwort that my goldfish tend to spit out the pellets i give them.
Fyi setup is about two weeks old but the hornwort was just added yesterday and one bunch is already shedding. The fish are young and are nibbling on the needles. Any advice?
There’s no problem with hornwort and goldfish and while the needles may prick them when they try to eat them, there’s nothing to worry about. Although they do tend to eat it less than other plants, which is a plus.
My shrimp love this plant but I was afraid to cut it as I didn’t know what to do,this article is clear and informative I’ll now cut and add to my other tanks.cheers richie
I’m glad this article helped. This plant can be a pain, but it’s one of my favorite ones out there.
When I bought mine hornwort, I was really happy to see all the NO3 going down. But after few weeks NO3 got really low (5mg/l), and looks like my other plants started to struggle. I even started to use fertilizers, but it was not helping much. So I took out 80% of hornwort from my aquarium, and suddenly the other plants started to look better. Is it possible that it steals too much nutrients from the water, so the other plants can struggle?
That’s definitely possible, since it grows so fast. It what makes it so good when you’re struggling with algae or for new tanks. Just keep it under control and you should be fine.
Hi there,
My hornwort is in a pond, placed about a month ago, and I have noticed it is starting to lose colour at the tips (turning a pale green/white colour) which fall off easily. Is this normal? If not, what is the problem? Thanks
It sounds like the hornwort has some nutritional stress. It might just be the stress from being newly added to the pond, but I would try adding some pond plant fertilizer to the pond first. Hopefully that will help.
does your pond exposed to direct full sunlight?
In an outdoor fry pond would hornwort grow better in full sunlight or under shadecloth. Thanks you.
It actually does well in both situations. Hornwort grows well in shade and full sunlight. How many hours of full sunlight does the pond receive?
do ever feed your hornwot and do you use co2 to grow them
Hornwort is an incredibly undemanding plant. I don’t use CO2 and I just add trace elements with each water change.
do they grow slow when the number of plants become to much?
As long as they have enough nutrients and access to light – something that may become a problem in dense growths – they will continue to grow until an aquarium is totally choked off.
How can i give them more nutrients except ferts by Adding more fishes and Feeding them twice a day?
Hello, Can the plant Hornwort be tied to submerged objects like wood or decorations without detrimental affects on the plant. I`m trying to avoid base rot and needle shedding . I hope that you can help me. Many thanks, Geoff in Yorkshire.
I’ve never had much luck tying hornwort to anything, as the stems are quite prone to breaking. While you’ll have some success for a while, eventually the plant will break free and you’ll have to tie it down again. Years ago, I gave up trying to plant or tie down hornwort and just let it float freely. The only place I really use it now are news tanks or breeding tanks. It’s too hard to make it look nice otherwise.
Thank you Robert.
Would you be so kind as to recommend plants that can cover the entire substrate yet grow slowly and remain small in size( under 25mm ). They are so many to choose from. Your advice would be much appreciated.
Geoff in west yorks.
I had this hornwrot in my tank one day whn I opened and checked all those leafs of these plants had came out n my tank was getting proper sunlight too!
Can we grow hornwrot without fishes in the tank?
You can grow hornwort without fish, but you’ll have to add fertilizer to the aquarium.
I have had this plant for years but this year it seems as if its rotting or very sick.. it looks very unhealthy. The stems have turned very dark green with algae like growth on it and what is left of the plant, the leaves,, also has turned this dark green almost black color. The pond gets a lot of sun but I have an umbrella shadding a lot of it . Mostly morning sun shade. Last year I had the umbrella in a different spot .. helping with the afternoon heat.. maybe that could make a difference 🤔. It gets up into the 100’s here in Texas so the water is warm but not too hot, I don’t think.. I’m not certain.. I have added 2 plants this year, .one philodendron and another tiny plant with skinny stems and round-ish leaves . Both are aquatic plants .. I looked it up to make sure.
Controlling the algae in this heat is hard but I’ve not had issues in the past years as bad.. I don’t know what to do to save my plants.
The pond is about 700 gallons with about 20 goldfish, mostly small but a few are pretty big. I only feed once a day. I put algae fix, pond clear, sludge destroyer, and plant food in. I tested the water and the numbers are good.
So .. what are your thoughts?? Much appreciated 🙏
What sort of filtration do you have on the pond? Do you have any waterfalls or anything to aerate it? Increasing either of those will help to control the problem.
Also, is there much debris in the pond? Old leaves? Other detritus? Removing these will help to control the algae as well.
And finally, the best way to control algae is to add more plants. The plants will out compete the algae for nutrients and should help to bring it under control.
In my tank huge amount of Hornwort there lives some ornamental fish Unfortunately fish can not move easily because of hornwort may cover or around by huge amount of algae. How can i remove huge algae or what i can do now ?
The best thing to do is remove the hornwort covered in algae. It grows so quickly it should spread again pretty quickly. Also, you want to deal with the source of the algae. Either lower the amount of hours the light is on or feed the fish less. One of those two things is likely contributing to the algae problem.
I changed a couple of my hornwort into the pond so that my guppy fry will have a hiding spot.
it’s a portable pond and it also has lotus and very little Cabomba (red). This is kept in a semi-shade, semi-direct sunlight spot.
Now, I’ve noticing part of the hornwort stem turning pale green. What can i do to save it?
It sounds like a nutrient deficiency in the hornwort. You could consider some pond fertilizers, however, you run the risk of algae blooms if you do that. Generally speaking, hornwort is quite hardy, and should survive even with low nutrients.
Excuse me Mr Brand,
So what’s the deal with hogwort? Can I use hornwort as a feature plant in my decorative fish tank? Will my exotic fish by affected by the hornwart plant (you know like in a funny way if you know what I mean)?
Thank you kind sir for taking the time to answer.
Love Rajah
I generally don’t recommend hornwort in a decorative tank. It often grows fast and spindly inside and when it sheds leaves, it can leave a tank unsightly. Hornwort is great in breeding and new tanks though, as its fast growth helps to keep the water clean and stable.
And as for the question whether it will affect your fish, it won’t have any harmful effects on any fish.
The plants in the picture are Myriophyllum not hornwort. Another article about hornwort has Limnophila pictures on his pictures. I understand that the plants do ressemble each other, but there is a great visible difference though…
It’s actually Ceratophyllum Submersum – a lesser known hornwort – which looks similar to Myriophyllum, but has notable differences.