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Here's a recent post in the El Natural forum that accused snails unfairly (I think) of bad behavior. I've put my response at the bottom:

"Well, I'm starting to have a snail problem. I've got probably 10 fully grown bladder snails and 1 pond snail. The pond snail has been munching my dwarf sag, crypts, and frogbit. There are currently 3 batches of bladder snails eggs on various plants. I went ahead and ordered a couple of assassin snails to take care of the problem!"

Snails are a helpful part of the NPT ecosystem (my book, pp. 44, 59). They break down larger food particles, thereby speeding up the decomposition process and nutrient release for plants. They help keep plant leaves clean of bacteria and algae. Their population seems to self-regulate in my tanks, which all have a wide variety of small snails.

Generally, snails eat dead and dying leaves not healthy leaves. That's because the leaves of most aquatic plants contain chemicals (allelochemicals) that repel snails. When leaves start to die, they release those chemicals and then the snails move in to feast on the decaying plant matter.

'The Aquatic Gardener' [Species Spotlight" by Rachel O-Leary (Dec 2017)], had a very nice article about potential problems of Assassin snails. For example, they are opportunistic predators and may prey on molting shrimp

IMHO, you are trying to correct a non-existent problem (at worst, a minor annoyance) with a greater problem. Assassin snails are very hard to get rid of. I would leave well enough alone.
 

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I have nerite, pond, ramshorn and trumpets in my tank. Nerite eggs everywhere can be a little annoying and something nibbles on my AR, possibly shrimp?? I don’t see a down side compared to the benefits they bring. And like you mentioned I don’t feel their populations are out of control. Just another creature to observe.


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Their population seems to self-regulate in my tanks, which all have a wide variety of small snails.
True statement here!

Overfeeding, dying plant matter will do nothing more than increase their numbers.
A hoard of snails can also leave a lot of "poo" behind.

Don't feed in excess and strive for premium plant growth, this will also inhibit algae.
 

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Fully agree, I don't understand this, currently very popular, hate against snails. None of my common small snails eat healthy plants and in fact I struggle to keep them alive. By their shells I assume that they don't have enough food in the competition with fish and shrimp, even if I try to overfeed and keep dying leaves in the tank..

The only two species which I get rid of as they munched on plants were apple snail (Pomacea bridgesii) and Brotia herculea.
 

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Among the bladder/pouch/pond snails, I find that Lymnaea DO in fact eat healthy-looking and young leaves of soft-leaf plants such as Nuphar and Frogbit. Physa or Physella pond snails and the usual red or brown ramshorns Planorbarius or Helisoma are not usually live-plant eaters (in my tanks and tubs). ANY snail can eat live plants if deprived of other food. Lymnaea have a right-handed spiral shell and wide flat triangular tentacles, while Physa/Physella are left-handed with longer thread-shaped tentacles. Common names are tossed around loosely and can be deceiving.
 

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Discussion Starter · #7 ·
Interesting and very well-put. Overall, I would expect some leaf-eating by certain snail species of more delicate plant species.

Almost all the snails in my tanks now are small, harmless Ramshorn. They seem to have out-competed the pond snails and Malaysian trumpet snails that I used to have.
 

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In my experience "pond" snails" (Physa) don't eat plants. For several years I have been trying to reintroduce then to my tanks, but apparently the fish eat the offspring. Now I have small populations in 2 tanks.

"Mystery" snails do eat plants with great gusto.

BTW, my first aquarium, a 15 gallon Metaframe from a neighbor who was moving when I was 12, came with a lot of plants and several species of snails. That was probably the most interesting tank that I've ever had.
 

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Great thread! I'm super new to the freshwater hobby so I'm not used to snails breeding in my tanks. I guess I may have possibly jumped the gun but seeing so many potential new snails just freaked me out a little. I honestly suspect that a pond snail (right facing shell spiral) may be the plant eating culprit. I really don't like the idea of these snails getting eaten but the good ol interwebs seemed to suggest bladder snails could get out of control. I guess I should have posted here before ordering the assassin snails but what's done is done I suppose. Should I try to cancel my order?
 

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In most of my tanks there are ramshorn, Malayan trumpet, and assassin snails. A few tanks have mystery snails. I've never seen damage to healthy plants that was caused by snails. In the mixed species tanks, assassin snails develop a normal predator-prey population balance with the other species.

The only snails that actually ate plants were the so-called rabbit snails, Tylomelania sp.
 

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Among the bladder/pouch/pond snails, I find that Lymnaea DO in fact eat healthy-looking and young leaves of soft-leaf plants such as Nuphar and Frogbit. Physa or Physella pond snails and the usual red or brown ramshorns Planorbarius or Helisoma are not usually live-plant eaters (in my tanks and tubs). ANY snail can eat live plants if deprived of other food. Lymnaea have a right-handed spiral shell and wide flat triangular tentacles, while Physa/Physella are left-handed with longer thread-shaped tentacles. Common names are tossed around loosely and can be deceiving.
You know much more about snail than I do, that's for sure :).

I don't know how what type of snails I have, they look like the one you get typically with plants. :) Relative small ones. I have not seen them eating any plants, or maybe I just do not notice? Anyway, plants are growing, that's sure.
What I see is, that over time, snail population reduces with time, but after the tank was set up, their numbers are growing for a while (for months..).
Do you think the decline in number is because they don't get enough food because organic matter is reduced in the tank, soil? I do have fish which I feed.
In another thank I have RCS and snails. Both seem to be able to easily maintain their population at this point (tank is only ~6 years old.) Do you think over time RCS or shrimp will out-compete each other?
 

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I am keeping several species of snails in all of my tanks and here are my observations:

Faunus ater (black devil) & Faunus sp (capuccino): both have been observed to eat sagittaria and valisneria leaves occassionally, on days that I forgot to put an algae wafer.

Physella acuta (bladder snails): only surface algae, usually gliding everywhere in the tank.

Lymnaea (pond snail): I used to have a single one and I had it for over a year, I remember seeing it munching on some plants before.

Helisoma (Red & brown variety): I have seen them scrape the undersides of ludwigia leaves, frogbits and are always on the egeria stems. Eats dead fishes, fish food & algae wafer & can reproduce much faster than bladder snails.

Melanoides tuberculata (Malaysian trumpet snails): I intentionally introduced 4 and are now countless after 3 months. Burried most of the time, I haven't seen them cling to any of my plants nor eating them. They look like miniature faunus when moving on the substrate.

Various Nerites (Clithon & Neritina): only surface algae (diatoms and green spot) and biofilm.

Assassin snails: They prefer ramshorn (and other kinds of food) over bladders snails. I have observed that they tend to eat smallest ramshorn first then moving up to the larger size and saving the largest one for last. They do attack cherry shrimps, two assassins attacked an adult cherry shrimp together a few days ago. However, the bladder snails in the assassin & shrimp tank are still alive and breeding up to now and they have been there for two months. They will not bother the nerites and faunus snails if there is a steady supply of ramshorn. In an lfs, I have seen a group of them attack a large apple snail. They will sometimes eat fish pellets, dead fish and algae wafer.
 

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Zolteec -- the common aquarium snails are pretty easy to identify to family or genus level. Do an image search for Ramshorn (Planobis, Planorbarius, Helisoma), Pond (Lymnaea), Bladder (Physa, Physella), and Malaysian trumpet or Melania (Melanoides). That covers the majority of "accidental" snails that often come with aquarium plants.

North American freshwater snails: http://www.fwgna.org/species.html
European FW snails: http://molluscs.at/gastropoda/index.html?/gastropoda/freshwater
 

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True statement here!

Overfeeding, dying plant matter will do nothing more than increase their numbers.
A hoard of snails can also leave a lot of "poo" behind.

Don't feed in excess and strive for premium plant growth, this will also inhibit algae.
It's true what you write, but the problem is that you are supposed to feed more food than the fish can eat in a Walstad tank, and this means that snail populations grow to a big number. I have the recommended Malaysian trumpet snails in my tank and also Planorbis planorbis (ramshorn?) that I got with plants I bought. There are lots of little snails all over the tank and I would like to reduce their numbers, although I don´t dare to add assassin snails.
 

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In my experience "pond" snails" (Physa) don't eat plants. For several years I have been trying to reintroduce then to my tanks, but apparently the fish eat the offspring. Now I have small populations in 2 tanks.

"Mystery" snails do eat plants with great gusto.

BTW, my first aquarium, a 15 gallon Metaframe from a neighbor who was moving when I was 12, came with a lot of plants and several species of snails. That was probably the most interesting tank that I've ever had.
Hi, what fish do you have that eat snails?
 

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Zebra loaches, Botia striata, are very good snail eaters. They are also beautiful fish, and are a good addition to a planted tank. I have used them a few times just to clear out massive colonies of snails. They do leave the shells behind, so that can be an eyesore.
 

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Discussion Starter · #19 ·
There are lots of little snails all over the tank and I would like to reduce their numbers, although I don´t dare to add assassin snails.
I'm sure that if worse comes to worse, the assassin snails can be called upon for major problems. But I continue to see juvenile guppies carrying around small snails in their mouth, presumably sucking out the contents. The guppies show so much determination. The baby snails must be very good live fish food!
 

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There are lots of little snails all over the tank and I would like to reduce their numbers,
Feed the snails to your phish! [smilie=b:

Get an old spoon, don't use your finger and gently smash the snails against the glass.
The phish will come running when they get used to this.

Finger will get infected from snail shell remnants if you get stabbed.
 
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