FROGBIT CARE GUIDE | How to Grow, Propagate & Contain It

Interested in getting floating plants for your aquarium? Try Amazon frogbit! Keep reading as I talk about why it’s so awesome, the best ways to grow it, and how to keep it from getting out of control.

I don’t know why I didn’t try floating plants before. I think I’m generally afraid of invasive things taking over my aquariums – whether they’re snails, guppies, or plants! But when I was researching plants for my Shy Guys tank, I really liked the jungle-y look of floating plants and the way it gives everything a green tint. I just haven’t much luck keeping them alive. My first floating plant was dwarf water lettuce, which I still love, but all the long roots fell off and the leaves disintegrated away. Same thing happened to my red root floaters – just massive amounts of die-off and melting. I did manage to save a few, but that’s a story for another time.

Finally, I discovered Amazon frogbit, also known as Limnobium laevigatum or smooth frogbit , and it’s awesome! It comes from tropical slow-moving waters in Central and South America, and unfortunately has become an invasive species in the United States via California. Therefore, do not flush this stuff down your toilet or put it in outside ponds where it can accidentally get caught on some bird’s foot and spread.

Frogbit is also known as South American spongeplant because it has thick, spatula-shaped leaves with spongy undersides that help with buoyancy. Supposedly snails like to eat the spongy parts, so just follow my plant dip tutorial and treat it with alum.

Pros and Cons of Frogbit

I really like this floating plant because the leaves are about 1-2 cm in diameter (at least in my tanks), so even though it can grow quickly, it’s much easier to remove than tiny little duckweed. I also love the long, fuzzy roots because they provide great hiding spots for shy fish and trap food for babies and shrimp to graze on. Finally, it’s great at removing excess nutrients from the water and totally got rid of all the stubborn algae in my betta tank.

However, I don’t like how floating plants get all of your arm and siphon when you’re trying to do water changes, so that was something I definitely had to get used to. Also, they readily multiply to the point where they cover the entire surface of your aquarium. That’s bad because a) the other plants don’t get enough light and b) your fish don’t get enough air because you need good surface agitation for oxygen to get replenished in your aquarium water. So, if you see your fish kinda acting lethargic or gasping at the surface, make sure to remove a bunch of frogbit or learn to contain it (details below).

How to Grow Frogbit

Everyone always says, “It’s so easy to grow, you don’t have to do anything!” But I’ve found that frogbit does best with the following conditions:

• Good planted tank light
• Good nutrients, such as Easy Green liquid fertilizer
• Not too much water on their leaves (although my frogbit does fine even with aquarium lids)
• Slow-moving waters to avoid breaking their roots

That’s also why frogbit is so hard to ship because the roots all snap off and the leaves melt if they get flipped over in the water. Luckily if you have at least a couple of surviving leaves with roots, you can usually grow a bunch more in no time.

How to Propagate Frogbit

As with most floating plants, frogbit is super easy to propagate. In the wild, they produce seeds from small white flowers, but in aquariums, they mostly spread via runners. Some people proactively pinch the new plantlets off, but I like to leave the baby plants or as long as possible (until they fall off on their own) because they seem to grow bigger and faster when they’re sharing nutrients with the mother plant.

How to Contain Frogbit

Okay, there are many reasons why you might want to do this, such as:

1. You need good surface agitation so that your fish get enough oxygen, but you want to keep the frogbit away from the areas with the strongest current so they won’t die
2. It’s really annoying to have your arm covered with floating plants every time you do a water change, especially when they fall outside the tank and make a mess of things
3. You want to make sure the other plants down below get enough light

In fact, for the Shy Guys tank, I wanted the frogbit to provide shade for the slow-growing anubias, but not cover up my fast-growing background plants. So, I made a ring out of airline tubing using a hot glue gun, and I clipped one end of the loop to an airline holder to keep it in place. When it’s time to do a water change, I unhook the loop from the airline holder and it floats on the water surface, containing all the frogbit even as the water level falls and rises.

Why is My Frogbit Dying?

I actually have 3 tanks that grow frogbit and interestingly enough, they do better in some environments than others.

#1 Betta Tank
This tank gets the most amount of light since the lid entirely made of glass (no hinge). The flow is relatively slow (using a USB nano air pump and sponge filter), and the frogbit is allowed to freely move (which means they take take turns getting under the strongest light). Therefore, the frogbit in here has the largest leaves out of all the tanks, reproduces the most quickly, and lowers the nitrates to only 5 ppm.

#2 Community Tank
The frogbit is contained and a bit overcrowded. Therefore, leaves don’t grow as big, but they do have the longest, lushest roots (because they’re protected from breakage and the tank is fairly deep). Also, I noticed that in one area of the tank, the frogbit always turned brown and mushy. It turns out that that section wasn’t getting enough light because the black plastic hood was blocking it, so I switched over to an all-glass top that hopefully will allow more light to spread.

#3 Shrimp Tank
The frogbit does the worst in this tank – the leaves stay tiny, turn yellow and develop holes, and then the shrimp eat them when they die. Now, there’s plenty of nutrients from the shrimp waste, but it looks like I still need to add more liquid fertilizers.

Question of the Day

What's your favorite floating plant? Comment below to let me know what you think. Take time to enjoy your aquariums and I’ll see you next time!

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