# Anacharis: The Fast Growing Stem Plant That Doubles as a Water Purifier I walked into that aquatics shop eighteen months ago planning to buy a goldfish bowl and some gravel. Forty minutes later I was staggering to the car with a 90-litre tank and more equipment than I knew what to do with. The bloke behind the counter had talked me into substrate, a filter, a heater, and three different types of plant, including what he called “anacharis for the cycling process.” I nodded like I understood what cycling meant and loaded it all into the boot.
That bunch of anacharis was the first thing that went right in my new hobby. While I was still figuring out water parameters and watching my first unfortunate fish struggle with the chaos I’d created, the anacharis just got on with growing. Fast.
Really fast. Two weeks in and it had doubled in size.
A month later I was trimming bits off and wondering what to do with them.
Six months later I realised this wasn’t just a plant that happened to survive my amateur efforts – it was actively cleaning up the mess I kept making with overfeeding and irregular water changes. Now I’ve got anacharis in all three of my tanks, not because I planned it that way but because it works so well I can’t bring myself to remove it. It might not be the prettiest plant in the hobby, but it’s possibly the most useful.
And after eighteen months of keeping planted tanks, I’ve learned that useful beats pretty every single time. ## Quick Reference | Care Level | Lighting Needs | CO2 Required | Growth Rate | Max Size | Our Rating | |————|—————|————–|————-|———-|————| | Beginner | Low to Medium | No | Very Fast | 3 ft (Bantam.earth) | 9/10 | ## Background and Natural Origins Anacharis, properly called Egeria densa, comes from South America where it grows wild in slow-moving rivers and lakes. The plant has been in the aquarium trade for decades, long enough that most aquatics shops stock it as a standard beginner option. What they don’t always mention is that this same plant has caused ecological headaches in places like North America and Europe, where it’s been introduced and decided it quite likes the local waterways.
The plant’s scientific name tells you something about its character. Egeria refers to a Roman water nymph, which seems about right for something that lives entirely underwater and spreads wherever it fancies. Densa means dense or thick, which describes both how the plant grows and how it forms underwater thickets when it gets established.
In aquarium terms, anacharis has been a reliable starter plant for new hobbyists since at least the 1960s. It’s cheap, it’s hardy, and it grows fast enough that beginners can see results quickly. The fact that it’s also excellent at processing the kind of water quality mistakes that new tank owners make regularly is just a bonus that the plant world happened to provide.
The plant grows naturally in water temperatures from 55–80°F and tolerates a pH range from 6.0–8.0 (Bantam.earth), which covers pretty much every freshwater setup you’re likely to encounter. This adaptability is what made it popular with fish keepers and what makes it a menace when it escapes into wild waterways. ## What Makes Anacharis Special The first thing you notice about anacharis is how quickly it responds to being put in a tank. Most plants take weeks to settle in and start showing new growth.
Anacharis starts growing almost immediately. I’ve seen new shoots appearing within days of planting, and the growth rate only accelerates from there. Stems can reach 40–100 cm in length with a width of 2–4 cm (Tropica), and in good conditions you’ll be trimming it weekly.
But the real magic happens underwater, where you can’t see it. Anacharis is what’s called an oxygenating plant, and it takes this job seriously. During daylight hours, when photosynthesis is running full tilt, you can actually see bubbles of oxygen rising from the leaves.
It’s particularly noticeable in the first few hours after the lights come on, when the plant seems to wake up and get straight to work processing whatever’s in the water column. This oxygen production is more than just visual interest. In a new tank, when beneficial bacteria are still establishing and fish waste is building up faster than the biological filter can handle it, anacharis acts like a living backup filtration system.
It pulls nutrients directly from the water, competing with algae for the same resources and generally keeping things stable while the tank matures. The plant’s growth habit is equally useful. Unlike many stem plants that grow straight up and then get leggy, anacharis tends to branch and spread, creating natural hiding spots for smaller fish.
When it reaches the surface, it doesn’t stop – it starts growing horizontally across the top, creating a canopy that provides shade and security for fish that prefer dimmer conditions. Propagation is almost embarrassingly easy. Cut off a piece about six inches long, stick it in the substrate or let it float, and within a week you’ve got a new plant.
I’ve accidentally propagated anacharis just by doing routine maintenance and dropping cuttings, which then rooted themselves in the substrate before I noticed. The plant doesn’t seem to care whether it’s rooted or floating, though rooted specimens tend to grow more vigorously. One aspect that sets anacharis apart from other fast-growing plants is how it handles different water conditions.
While many plants are picky about hardness or pH, anacharis adapts to whatever you give it. I’ve kept it successfully in soft water at pH 6.5 and in hard water at pH 7.8, and the growth rate was nearly identical. The only condition that seems to slow it down significantly is very soft water with no dissolved minerals, but that’s rare in most tap water supplies.
The plant’s appearance changes subtly with different conditions. In high light, the leaves become more compact and the plant takes on a slightly bushier appearance. In lower light, it stretches more, with longer internodes between leaf clusters.
Both forms are attractive in their own way, and the plant’s ability to adapt its growth pattern to available light makes it useful in a variety of tank setups. ## The Honest Assessment Anacharis isn’t perfect, and after eighteen months of keeping it, I’ve encountered most of its limitations. The most obvious issue is that it doesn’t know when to stop growing. What starts as a neat bunch of stems quickly becomes a jungle that can overwhelm smaller plants and dominate the visual space in a tank.
You Might Also Like
Regular trimming isn’t optional – it’s essential maintenance that you’ll be doing weekly once the plant gets established. The plant’s success as a nutrient absorber can also work against it in very low-nutrient environments. In tanks with minimal bioload and efficient filtration, anacharis can start showing signs of nutrient deficiency, particularly potassium and iron.
The leaves may become pale or develop holes, and growth slows noticeably. This isn’t common in most community tanks, but it can happen in very clean, low-stocked setups. Temperature sensitivity isn’t usually an issue, but the plant does have limits.
While it tolerates the 55–80°F range well (Bantam.earth), it really doesn’t like sudden temperature changes. A rapid drop can cause massive leaf shedding that makes a mess of the tank and requires significant cleanup. I learned this the hard way during a heater failure last winter.
Salt sensitivity is another limitation that caught me off guard. The plant deteriorates in water with salinity ≥2 g/L (AquariumBreeder), which means it’s not compatible with tanks that use salt as a medication or stress reducer. This rules it out for some brackish setups and limits treatment options if fish health problems arise.
The plant’s invasive nature outside of aquariums is worth considering from an ethical standpoint. Anacharis is classified as a noxious weed in several countries because of its impact on native ecosystems. While this doesn’t affect its performance in tanks, it does mean that disposal needs to be handled responsibly.
Never dump aquarium plants in local waterways, and always compost trimmings rather than disposing of them where they might reach natural water sources. From an aesthetic perspective, anacharis is functional rather than beautiful. It doesn’t have the dramatic colours of rotala or the elegant structure of ludwigia.
It’s green, it’s bushy, and it gets the job done, but it won’t be the centrepiece of any aquascape. Some hobbyists find its utilitarian appearance off-putting, especially in tanks where visual impact is the primary goal. ## Legacy and Influence in the Hobby Anacharis has shaped the planted tank hobby in ways that aren’t immediately obvious. For decades, it’s been the plant that teaches new hobbyists what healthy plant growth actually looks like.
Before planted tank forums and YouTube channels, many beginners learned about plant care by watching anacharis respond to changes in lighting, fertilisation, and water parameters. Its fast growth and obvious reactions to different conditions made it an excellent teacher. The plant’s role in biological filtration has influenced how many aquascapers think about plant selection.
The concept of using fast-growing plants to control water quality during tank startup is now standard practise, and anacharis was one of the first plants to demonstrate this principle clearly. Modern planted tank cycling methods often rely on this same approach, using quick-growing species to establish biological stability before adding more sensitive plants and fish. Anacharis has also contributed to the development of low-tech planted tank methods.
Its ability to thrive without CO2 injection, high-intensity lighting, or complex fertiliser regimens proved that successful planted tanks didn’t require expensive equipment or advanced techniques. This opened the hobby to aquascapers who couldn’t afford or didn’t want to manage high-tech systems, significantly expanding the planted tank community. The plant’s reputation as a beginner species has sometimes worked against it in more advanced circles, where it’s dismissed as too basic or unsophisticated.
But experienced aquascapers often return to anacharis when they need reliable performance for specific functions: nutrient absorption, oxygen production, or temporary biological stability while other plants establish. Its unglamorous reputation doesn’t change its effectiveness. Recent trends toward natural and low-tech aquascaping have renewed interest in anacharis among experienced hobbyists.
The plant’s ability to create natural-looking underwater meadows and its excellent compatibility with fish that prefer planted environments has made it popular in biotope tanks and community setups focused on fish welfare rather than visual perfection. ## The Verdict After eighteen months of keeping anacharis in multiple tanks, I can say without hesitation that it’s one of the most useful plants in the hobby. Not the prettiest, not the most sophisticated, but absolutely essential if you want a planted tank that just works reliably. It’s the plant equivalent of a good PE teacher – not flashy, but gets results through consistent effort and doesn’t give up when conditions get difficult.
For new hobbyists, anacharis is almost mandatory.
It’ll keep your water clean while you learn how everything else works, it’ll grow fast enough to give you confidence that you’re doing something right, and it’ll survive the mistakes that kill more finicky plants. The fact that it costs about £3 for enough to fill a 60-litre tank makes it accessible to anyone starting out.
Experienced aquascapers shouldn’t dismiss it either. Yes, it needs constant trimming and it’ll never win aquascaping competitions, but it’s unmatched for specific applications. Need to cycle a new tank quickly?
Want to add biological stability to a heavily stocked setup? Looking for natural fish behaviour in a community tank? Anacharis delivers results that expensive, exotic plants simply can’t match.
The plant works best when you accept what it is rather than trying to force it into roles it’s not suited for. Use it as a background plant, let it do the heavy lifting on water quality, and trim it regularly to keep it under control. In return, you get the most reliable planted tank performance you’re likely to find in any species.
See where anacharis placed in our full ranking of aquarium plants – spoiler alert: higher than you might expect.
