When it comes to the top level of planted aquaria, you’re not short on options. There are a wide variety of different plants out there that can provide shade, oxygen, and even a bit of food for the fish contained in your aquarium. Willing to learn a bit? Read on, and I’ll show you some of the best and describe their use in a planted tank.
1. Amazon Frogbit
Amazon Frogbit is a personal favorite, particularly in tanks where low lighting is necessary to keep species like Anubias safe from excess algae. The long, flowing roots create a “jellyfish” effect that many love, although the plant takes some work to truly thrive.
It multiplies quickly; each leaf has the ability to create a whole new plant. The exponential rate of growth doesn’t take much. Lighting in the 2-3 watt per gallon range and a little bit of carbon dioxide goes a long way.
There are two obstacles to its growth in aquaria. The first is that the plant can rot if the top gets too wet. It’s an odd “feature” for an aquatic plant, but it happens. Keep it away from your HOB filter for the best results, or at least keep the tank filled enough; there’s no splashing.
The second is that snails like to chew on the underside of the leaves. It’s not a major issue in most colonies, but overpopulation can kill your Frogbit.
Any planted tank owner with snails should have an Assassin Snail or two in a bowl somewhere. Pick one up if you’re planning on enjoying Amazon Frogbit.
Whether you create a small patch of it in the corner or use it as the primary cover in your tank is up to you. It’s a unique plant but still beginner-friendly in a well-kept tank.
Hornwort is easy to find, and it grows remarkably well underneath low lighting. There’s not a whole lot to caring for it, but it’s not always the best option for newbies due to a few simple caveats.
My main problem with it is that when it dies, it drops needles. These create a huge mess, and the total bioload added to the tank can be rather high. If you run into it, then it’s best to just remove any yellowed portions of the plant, and vacuum siphon the bottom of the tank.
When not dying off, however, Hornwort is a vibrant plant. It thrives in lighting conditions from 1-2 watts per gallon, but if you go any higher, you’ll be trimming it often. It’s low maintenance in chemistry, but its rapid growth means frequent trimming is necessary.
Hornwort can be planted in the substrate as well. This planting is often temporary, however, as the stalks will rot when not exposed to light, and the plant will eventually break free. If you’re using it as a bunch plant in your aquascaping, then you can expect to replant every few weeks.
Despite the few setbacks that come with it, it’s a vibrant and beautiful plant. There are a few varieties of floating plants that match its description. Still, as a general rule, they’re much harder to keep.
Give it a shot if you’re a newbie, just let it float and grow. You’ll be amazed at the results in just a couple of weeks.
3. Giant Duckweed
Duckweed has a mixed reputation among aquarists. On one side, it adds a dark green and well-textured beauty to the top of the tank.
On the other hand, it grows so well in the nutrient-rich environment of an aquarium that it’s almost impossible to remove once it’s taken root in a tank. Even a single piece of it left in a tank will quickly multiply. The exponential growth pattern also means it needs constant control, or it can overgrow the tank, shading the entire bottom.
The “leaves” range from 5-9mm, averaging about 6mm, which makes it rather impressive in size for the genus that contains it. It also makes it easier to remove if you decide that it’s not for your tank.
As a general rule, Duckweed thrives on nitrate in the water and acts as a good nutrient sink. Too much of it can make a mild problem for airbreathers, such as Gourami or Betta. A couple of dips of a net can give them the clearance they need.
It’s green, has a unique look at the surface, and helps provide shade and cover. It’s hard to beat in a planted tank, just don’t confuse the giant variety for it’s smaller cousins. Giant Duckweed is a hit, as long as you have time to do some minimal maintenance.
4. Java Moss
Java moss is… well, it’s a huge part of the aquarium trade. I can virtually guarantee you’ll be able to not only keep it alive but also make it thrive no matter what your experience level is.
Java moss is often found “rooted” to rocks or driftwood. What many people don’t realize about this hardy plant is that it can also exist in floating clumps. It makes excellent, dense cover for fish like Betta while still allowing them to get air.
You can just float it by itself, but the chances are that it’s going to end up in the filter that way. Instead, you should try attaching it to something which already floats.
My personal favorite? A cut off piece of a wine cork sourced from a craft store. Just don’t use a wine cork which was in a bottle. The leached chemicals from the wine can be quite toxic. From there, a t-pin, or even a bit of fishing line, will hold the plant in place as it grows.
Java Moss isn’t limited by water conditions, light, nutrients, or even the skill of the person growing it. Just be aware that removing it from a tank permanently may require full sterilization. That said, it’s not as invasive as Duckweed, and it can be grown in high light conditions without adding a ton of work to your life.
Cabomba is superficially similar to Hornwort, but it provides you with a much greener backdrop. The plant is also less prone to creating large amounts of waste, but it’s a bit harder to grow in aquaria than many other floating plants.
Cabomba is nominally a stemmed plant, but it does excellent floating in the tank. It can even bloom while floating, which means that it can thrive. The mistake that most newbies make is not giving it enough light: Cabomba thrives in conditions of 2 watts per gallon or more. It will die off after a couple of weeks if the lighting is low.
Liquid fertilizers and CO2 are both necessary for the plant to grow well. If your stems look sparse after they’ve begun to grow, you’ll need to up one or the other. It’s a nutrient hog but not an excellent nutrient sink like Anacharis or Hornwort.
If you’re a newbie, then do your homework before investing in the plant. Particularly if you’re going down the colored route. Most people will find that it’s a solid addition to their aquascape, and it’s a great plant to cut your teeth on.
Azola, or Mosquito Fern, is a mat-like plant that covers the top of the tank. The red and green coloration is attractive, and the roots provide good cover for small fish and invertebrates. It’s most commonly used in ponds, but I’ve found it’s also a beautiful addition to the aquarium’s surface.
Azolla grows quickly, and you can limit its growth by monitoring the coloration. In its natural environment, it turns red in the fall or under bright sunlight. If it begins to turn red early in its lifecycle, then you’re likely running high in nitrates.
Take a lesson from pond owners, and you can use it as a “canary in the coal mine.”
Under optimal conditions, Azolla will grow exponentially. Unlike Duckweed, however, I’ve found it much easier to keep under control if you only want it across a portion of the tank’s surface. Use a fishing net to remove any excess, and remember that the plant generally doubles in size every 24 hours once established.
Mosquito Fern is a great departure from the usual top plants. The primary condition for it is just limiting growth. Still, it’s much easier to control than some of the other aquatic “matting” plants out there.
7. Dwarf Water Lettuce
Have you ever wanted a matting plant that grows above the surface of the aquarium? If so, then try Dwarf Water Lettuce. It’s a hardy, productive plant that’s easily removed and managed.
The plant is originally from the Nile River in Egypt. Since then, it’s spread to most waterways in the world. Anywhere that tropical or sub-tropical freshwater can be found it grows. It’s considered invasive, but it doesn’t grow as quickly as many invasive matting plants.
Management and growth are easy with Dwarf Water Lettuce, which makes it ideal for those who don’t have a green thumb. The roots beneath are great, mimicking Frogbit but a bit longer. They provide excellent cover for small animals and invertebrates.
It also serves a mosquito habitat. Don’t use it for ponds or outdoor aquaria if you can avoid it.
Still, it’s a beautiful plant and much easier to control than many that float on the surface of the water. In a well-cycled tank, it’s easy to manage. It’s a stunner when appropriately treated, and the ease of growing it will quickly become apparent.
Pick it up for a whole new look to the top of your tank.
Crystalwort, better known by its Latin name Riccia fluitans, is often used as a ground cover in planted aquariums. The truth is that it’s actually a floating plant when found in the wild. It’s also not as demanding of nutrients and light if you allow it to grow naturally.
Use as a ground cover was pioneered by Takasha Amano, whose techniques form the foundation of most modern planted aquaria.
The plant can be treated much like Java Moss in the aquarium. The Japanese type is also suitable for ground cover by weighing it down. It thrives best as a floating plant, however, and you’ll see good growth with CO2 and lighting of 1.5-2 watts per gallon.
It’s often cultivated this way for other uses as well. In the past, I’ve maintained tanks that used floating Riccia fluitans to protect fish or shrimp fry. During the process, I’d move portions to other aquaria for use as ground cover.
That said, on its own, the dense growth and vibrant green make it an excellent choice. If you feel like Java Moss is a bit played out, but you still want a dense, stringy cover take a look at some Riccia: it may be just the change you’re looking for.
9. Floating Bladderwort
Looking for something unique?
Floating Bladderwort is a carnivorous plant that floats at the surface of bodies of water. It forms thick, dense mats that trap microfauna in the water column. It’s not quite a Venus Fly Trap, but those who know how it feeds will find them fascinating.
Bladderwort is another floating species that is easy to cultivate. It’s suitable for those at any level of experience with plants. The thick mats created are easily sorted and trimmed to proper lengths. It grows quickly, but it’s not as “invasive” as many plants on this list.
Bladderwort lacks any sort of roots. It’ll grow as long as the tank is cycled, and there’s no need to interfere beyond trimming. Even CO2 is unnecessary; it gets its nutrients from the micro-crustaceans and freshwater insects it captures.
Due to its newbie-friendly nature and unique looks, Bladderwort definitely makes our list. Give it a shot, just be aware that your tank should be fully cycled, and have something of an ecosystem going before you bring it into play.
Elodea sp. are extremely common. Anacharis is the most common variant, the specific species name for it is Elodea densa. You’ll see it recommended a lot for a lot of different things.
The reason is simple: Elodea species are all hardy plants that grow exceptionally well in captivity. Some are invasive in the wild due to their adaptable nature.
As a floating plant, it’s excellent. It requires almost no care, propagation can be done with a sharp pair of scissors, and its growth rate is manageable. The plant remains viable in higher lighting. Some others will need daily maintenance above 1.5 watts per gallon.
The only reason not to add it to a tank is that it’s the “newbie plant.” I strongly recommend it, alongside Java Moss, as the best plant for someone new to planted aquaria. Even if you don’t plan on keeping it, it makes a great nutrient sink until the tank is cycled properly.
Anacharis is pretty much a “fire-and-forget” sort of plant. Put it in the tank, and it’ll thrive as long as there are light and a couple of fish.
When to Use Floating Plants
Floating plants can be used alone or as part of your aquascaping. They’re not used frequently as part of formal landscapes. Both the Dutch and Japanese styles of aquariums have relatively strict rules to qualify, after all.
Unfortunately, floating plants rarely make the grade, so they’re not used as often in high-end tanks. That leaves a lot of would-be aquascapers wondering how to utilize them.
Jungle tanks often benefit from some floating plants, especially when they’re planned well. But you can do more than just leave them hanging.
If you’re keen on adding them to your aquascape then you should consider the following uses:
- Shading: Intent on growing slow-growing plants like Anubias in a tank with high-lighting? Consider floating plants. You can use them to create shaded areas with a little bit of corraling.
- Adding Motion: You can use lighter stemmed plants to create a moving effect in your aquascape. Small portions of plants like Hornwort can be pushed underwater by a HOB filter before rising and returning in the current to repeat it. Done properly, it’s a unique, eye-drawing feature.
- Open Tanks: Top dwellers like Frogbit are a fantastic addition to hoodless tanks. They provide texture and color above the normal waterline.
- Preventing Jumpers: Some fish like to jump. Zebra Danio and Killifish, for instance, are notorious for leaping out of open-top tanks. Floating plants will often keep them from jumping. Or at least reduce incidents.
Get creative with it!
Floating plants are underutilized, in my opinion, but they do require some special maintenance and planning.
Maintaining Floating Aquarium Plants
When you’re setting up a tank to include floating plants, you need to keep a few things in mind. I’ve split these plants into categories to make it a little bit easier.
Floating stems are the easiest. All you need to do is trim them down when you think there’s too much. Some, like Hornwort, will grow exceptionally fast. Cabomba, on the other hand, grows more slowly and won’t require as much.
If you’re careful, you can trim just above the growth nodes at an angle with sharp scissors. This “topping” can create extra branches that result in denser coverage.
Frogbit, Watter Lettuce, and others require a different approach. This starts with the tank’s design.
Many people have failed to keep these plants over the years. The reason is simple: they’re not going to do well in a closed-hood tank. You need to have the top of the tank open to the air.
There’s another reason to be careful: many people have their lights only 2-3″ above their tanks. For these plants to thrive, instead of simply getting burnt, you’ll need to raise the fixture.
6-8″ above the tank is good, but it will reduce the lighting at the bottom of the tank. Try not to use them in tanks which are over 24″ in height. Plants that require high lighting may need to be raised on tiers.
Planning aside, these plants are remarkably easy to keep.
Matted plants generally require two things: an open hood and nutrients. As long as these are in place, the majority of them will thrive. Some, like Duckweed, are almost impossible to get rid of.
Cutting them back is the primary concern. If you’re willing to thin them out frequently, you’ll find the dappled shading effect pleasing. On the other hand… they’re a lot of work.
Keep them thinned down to manageable levels, especially if you don’t have powerful lighting in the first place. They’re hard to corral, and most grow exponentially, but they can provide a fantastic look when used carefully.
We’ll All Float On!
Floating plants are low maintenance and hardy for the most part. It’s generally more work cutting them back than making them thrive as long as you plan them out. They’re an important part of your aquatic ecosystem, but the real draw is always their unique beauty. Try out some of the above, and you’re sure to see why they’re so common in the trade.