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What is wrong with my frogbit?

19847 Views 20 Replies 9 Participants Last post by  Dolfan
I got some frogbit a while back and it is generally doing very well. The only problem is that many of the leaves are developing small holes in them. It almost seems like they are being eaten my shrimp. Is that possible? I have a lot of cherry shrimp, a few ghost shrimp, some MTS, and an occasional pond snail which I remove when I see them. The shrimp love hanging out under the leaves and on the roots and occasionally it looks like they could be eating the leaves, but not really sure. Could any of the tank fauna be eating the leaves. The leaves developing the holes are occasionally an older yellowing leaf that is submerged or dying, but it is often a green otherwise healthy looking leaf. I trim the affected leaves every day, and the next day there are a few more to trim out. Also, other plants I have in the tank seem to be doing fine, like hornwort, bacopa, java moss, and java fern

As for tank parameters and ferts....
40 gallon breeder with tetras, otos, shrimp, snails, and 1 bristlenose pleco
My ammonia and nitrite are always at 0.
Nitrate is usually low around 5ish and maybe up to 10 after adding ferts.
Temp is at 74F.
I use Flourish Comprehensive 2 times per week
Flourish Nitrogen, Phosphorus, and Potassium 2 times per week.
3 CFLs 18w 6500k for lighting
SunSun HW-302 and 2 sponge filters for filtration.

Any ideas? Is it the shrimp? Nutrient deficiency? Anything I can do to help? Thanks in advance for any insight and/or tips.
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Pictures ?
Here are a couple pics I took. They aren't the best but you can see a few of the leaves with holes in them. Can shrimp eat the frogbit? I try to feed them sparingly as don't want any overfeeding problems, but maybe they are hungry so trying to snack on the frogbit.

Green Leaf Aquatic plant Annual plant Pond

Green Leaf Annual plant Groundcover Aquatic plant
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Is your tank open topped? I'm not sure but I think I am right in saying that condensation dropping onto the leaves can cause this.
No, I have an open air tank. So it's not water droplets magnifying the light. Anyone else with any ideas?
Rhopalosiphum nymphae aka aquatic aphids. Get a magnifying glass & look at the edge.

Once aphids are in your tank, it's near impossible to remove them without pulling all the floaters. You can crush them but they jump out of the way faster than you can move.

I've used a torch/lighter to set aphids on fire & it works well, but it will also damage the plant. Flame kills aphids almost instantly.

  • Neem oil is a good liquid spray to use & I have some for the garden, but not sure if it's harmful to shrimp. Use at your own risk.
Could I take out all the floaters and do an Alum dip like what I do for new plants to prevent snails? Would that kill them off?
No, I have an open air tank. So it's not water droplets magnifying the light. Anyone else with any ideas?
I never thought about the magnification I always wondered why exactly droplets were bad - thanks for that :) Have you ever had your frogbit die off over time? mine used to grow so well I would give it away to friends then towards the end of last year it gradually died off leaving smaller and smaller plants before disappearing completely - at the same time in all our tanks?
I see some of this in my tanks. It does kind of look like bug damage and I did early on see some tiny bugs when I first got it. Some of it may also be due to water as others have mentioned. even with an open top water can splash up over the foliage or just accumulate and cause breakdown. I don't worry about it as the growth far exceeds any damaged plants.

If it is bugs...I wonder if you could do light spraying of something like hydrogen peroxide on the frogbit? I'm not sure if it would kill the tiny bugs or not...but wouldn't be harmful to the tank in light doses every other day or so. Might research it, I don't know how frogbit would respond to HP.
I have no idea if alum will work, but I can tell you that even KMnO4 doesn't do much.

Certain types of fish will eat them, but most fish will spit them out. Seems like they prefer the commercial foods more than these little sap sucking bugs. I've stopped trying to eradicate these things until someone has a decent natural suggestion.

While typing, I just came up with an idea that involves a steamer that I bust out once a season usually around this time of the year. What I plan on doing is "SEAL" the tank & pump it with 200+ degree Fahrenheit water molecules.
I've dealt with aphids on my floaters before. Food grade diatomaceous earth kills them if it stays dry. You can submerge your floaters in a tank with endlers or microrasboras and they'll feed on the aphids. The last thing you can do is toss out most of your infected floaters, keep the clean floaters submerged for a week or two to keep the aphids from hatching.
How do you keep the plants submerged? I always find a ton these aphid find spaces to hide so they stay out of the water, but they're near microscopic it's hard to tell how many you're actually dealing with.

I got rid of all my endlers type fish years ago & the wild livebearers I have are too picky to eat aphids. Copepods they love though.

MF, you're method will work, but requires 1-2 weeks to be sure.

Flame method will work immediately, but has a limited range & it will damage the plants. Fun though if you're talking on the phone.

  • Can you use FG DE if you have shrimp in the tank? I assume no because they're similar to insects in some ways.
  • Would shrimp have issues if they consume DE residue?
It is certainly possible that insects are causing the holes, or possibly even stagnant water drops on the leaf's surface. It may also be potassium deficiency though.

It can sometimes show up strangely in floating plants. See the thread below for photos in tiger lotus.

Are your other plants showing holes in the old growth? Usually stem plants have tiny holes compared with lotus plants and floating ones.

Can you take more photos but super close up so we can inspect the edges of the holes?
I use a 32oz clear soup container or a clear container of similar size. I fill it up with water, toss the floaters in, toss some craft mesh over the top of the floaters, then I weigh down the craft mesh with another container that's heavy enough to push down the naturally buoyant craft mesh and floaters.

I never used FG DE with the floaters in my shrimp tank so I would have no idea how it would affect your shrimp. DE earth will clump up when exposed to water though. I treated the floaters in a shallow bin as sort of a quarantine. The aphids didn't like the DE earth much and they slowly disappeared.

Fire would be nice to use if it didn't burn the leaves of dwarf water lettuce or other floaters.

Sometimes I find a few small hopping insects on my floaters. I'm not sure what they are but they're definitely not aphids. They don't seem to affect the plants at all.

The floaters reproduce so fast that you only need a few plants to start over so it's easier to purge the infected stuff than to treat it all.
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My other plants seem to be fine, that is why I don't think it is some sort of nutrient deficiency. I could be wrong though. I tried doing an alum dip/bath yesterday for 5-6 hours. I would check on them every hour or so, and stir up the water a bit and push the plants down to submerge them. I figured the alum would kill the aphids as well as possibly they would drown if constantly submerged. Assuming that it is aphids. I'm also pretty sure it's not magnification of the light from water droplets. I don't have very strong lights, just 3 CFL's, 18 watts each, 6500k.
It is possible that you wouldn't see potassium deficiency holes in other plants given the setup.

The floating plants are nearest the light, have the most CO2, heat and light, which all control the plant's metabolism and ramp it up much higher than your other plants beneath them. It is exactly these plants that I'd expect to see the first signs of deficiency in.

If it is a deficiency of potassium no newly formed leaves will be damaged, only the slightly older ones. From the look of the photo this seems to be exactly the pattern in your plants. Can you double check it in person?

Also, is there any way you can add more potassium to the tank? K2SO4 (potassium sulfate) is a great source of potassium and will quickly rule out potassium deficiency issues if added. If it isn't potassium problems then you can start figuring out what else it might be.

Aphids are very easy to see on plants, you'd notice them if you looked closely.
i definitely think that's a deficiency
i kept frogbit outdoor with sunlight

i put some compost in there as nutrient source. whenever they got a bit crowded i took some and place it in my indoor tanks. those ones aren't doing so well and got the same holes like in your photo.
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I dose with Seachem Nitrogen, Potassium, and Phosphorus 2-3 times a week. I add the normal dosage listed on the bottle for my tank size. I also use Seachem Flourish Comprehensive 2 times a week in between doses of the macros. Could it still be a deficiency?
Yes definitely. SeaChem fertilizers are known to be quite dilute by EI standards. If you have any kind of plant density in the tank all the nutrients you are adding could be used up leading to chronically low/deficient nutrient levels.

Potassium usually shows up first in these kinds of long term chronic nutrient shortage conditions. Have a look for yourself using wet's according to EI's recommendations (to ensure unlimiting conditions) you should be adding 46 mL 2-4x a week (total of 92 - 184 mL a week). This is also why most of us have switched to using dry fertilizers instead of premade products. It is just too expensive to use liquid ferts.
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