# Species list of invasive aquarium snails



## illustrator (Jul 18, 2010)

Dear all,

I am working on an article for a local aquarium magazine and would like to double check which "invasive aquarium snails" we all have. There are a number of common misidentifications, but it appears that we share the same species worldwide. Please tell what you think of the following list including the scientific names. Am I missing something or still misidentifying some species?

*ramshorn snails*: _Helisoma duryi _& _H. trivolvis_, originating in North America. The European ramshown (_Planorbarius corneus_) is not a nuisance species in aquaria.

*"small ramshorn"*: _Gyraulus_ sp. Do we have _G. sinensis _(from Asia) as the nuisance species or is it another one?

*bladder snail*: _Physa acuta_, originating in North America, but the type locality is in France. Is what we sometimes call _P. marmorata _from aquaria just retarded _P. acuta _or do we really have two species in aquaria?

*trapdoor snails*: _Melanoides tuberculatus_ and _Tarebia granifera _originating from Asia/Africa. Of both species there are multiple clones in aquaria, which differ in shell colour and morphology.

*pond snail*: _Pseudosuccinea columella_, originating from North America. I have seen the same snail(?) identified as _Radix rubiginosa_, originating from Asia. Which identification is correct or do we have two species in aquaria?

*faucet snail*: _Bythinia_ sp. not very often seen and always in small numbers. Has anyone identified it further? The ones I have seen appear different from _B. tentaculata_: the shell is shorter, more the shape of an apple snail. These are very small snails, perhaps 4 mm.

I'll cross-post this on seriously fish, hope that on either one forum I'll get some additions!


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## Tugg (Jul 28, 2013)

Here's an thread I posted about a year ago on a different forum:

http://www.dfwfishbox.com/forums/pr...hp?35436-General-Freshwater-Snail-Information


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## illustrator (Jul 18, 2010)

Have to add this one:

*Freshwater limpet*, _Ferrissia fragilis_, originating from North America


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## miremonster (Mar 26, 2006)

Interesting project. Also for me because of partly outdated, insufficient or still wanting entries in the Flowgrow invert database...
True ID of the aquarium snails has surely a more general relevance, beyond the hobby and trade, because of worldwide spread of alien species via aquaristics, etc.

I suggest to list here also articles resp. publications dealing with determination of aquarium snails. It's also important to know where the used names are based on, in order to assess the reliability of the ID's and to read the crucial characters of the species. There's a popular aquarium snail book in German with quite many species ("Schnecken-Fibel"), but it doesn't cite any sources.

One snail comes to my mind now: Potamopyrgus antipodarum. http://en.wikipedia.org/wiki/New_Zealand_mud_snail Longer time ago I had temporarily masses of tiny prosobranch snails in my tank and I can only guess they were P. antipodarum. Such snails are also occasionally shown in aquarium forums and are believed to be e.g. Bithynia tentaculata. On some aquarium websites P. antipodarum is treated as aquarium snail. But I couldn't find out by what means the snail was determined.

Another case: "Thiara winteri", also treated under that name in the above mentioned book, but I suspect that all "winteri" in the hobby is Th. scabra that's also known as invasive species in several regions. Who could clear up that? And to what extend is the presence of spikes on the shell dependent on the environment? 
The Thiara scabra is apparently also often confused with Tarebia granifera in the hobby.


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## miremonster (Mar 26, 2006)

Another name can be found especially in older aquarium literature: Helisoma nigricans. Today a synonym of Planorbella nigricans. I don't know how it differs from P. duryi and P. trivolvis, but perhaps it still occurs in tanks as well. Flora Europaea lists Planorbella duryi and nigricans: http://www.faunaeur.org/full_results.php?id=430557

I wonder if also tropical Old World ramshorns such as Indoplanorbis exustus can be found in aquariums, maybe introduced with plants from Asia: http://en.wikipedia.org/wiki/Indoplanorbis


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## Cavan Allen (Jul 22, 2004)

I don't consider _Gyraulus_ to be pests. They are VERY effective glass and plant cleaners. Wish I still had them! They can be pretty numerous, I'll admit.


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## illustrator (Jul 18, 2010)

I think that most snails are not pests in aquaria, MTS also not for instance. It is a different matter when they end up in nature. Not only the visible effects have to be considered, but also effects on micro-organisms and on related native species. Effects of small snails are difficult to research, but considering that they can be(come) extremely numerous, I would be very surprised if there aren't any effects. Simplified: very numerous snails all have to eat something, and that something was either not eaten before they were there, or eaten by some native species.

In literature parasitic diseases are increasingly often mentioned in connection with alien species. Many of the "aquarium snails" are potential intermediate hosts of flukes (MTS are often mentioned in this respect). The populations of snails in aquaria are almost certainly free of flukes, but the snails come in contact with flukes once they are "escaping" to nature. When the snails multiply to very high densities, also the flukes reach such high densities and cause a health risk for many species, including humans.

In another case, massive die-off's of waterfowl are described which are connected with an invasion of _Bithynia_ snails and a intestine worm which is having the snails as intermediate host. These snails also occur in aquaria, but what I have seen so far, their numbers in aquaria are very low and they normally go unnoticed. They are definately not a problem in aquaria. But they are once they get to nature. See for instance: http://www.dnr.state.mn.us/hunting/waterfowl/scaup.html or http://pubs.usgs.gov/of/2007/1065/pdf/ofr_20071065.pdf

So with "invasiveness" I don't mean their effects in aquaria, but in nature.


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## illustrator (Jul 18, 2010)

miremonster said:


> I wonder if also tropical Old World ramshorns such as Indoplanorbis exustus can be found in aquariums, maybe introduced with plants from Asia: http://en.wikipedia.org/wiki/Indoplanorbis


What is the difference between _Indoplanorbis_ and _Helisoma_? I didn't know _Indopanorbis_, but it looks pretty similar when I google it.

I know the European _Planorbarius corneus _well, and this species is about twice the size as _Helisoma_, when well fed. So this is relatively easy to determine, just put a few snails in a glass jar and feed them with (dry) catfood for a while so they can reach their maximum size (frequent water changes are needed, otherwise the water goes faul very quickly with this diet ... ) .


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## miremonster (Mar 26, 2006)

illustrator said:


> What is the difference between _Indoplanorbis_ and _Helisoma_? I didn't know _Indopanorbis_, but it looks pretty similar when I google it.


I have not yet found out that. I found the name I. exustus first in a German-speaking forum where someone claimed that according to a website (which?) this snail hunts for planaria.
In the Wikipedia article: "Planorbella duryi and Biomphalaria pfeifferi have similar shells.[8]" Source: http://en.wikipedia.org/wiki/Indoplanorbis#cite_note-Kristensen_1987-8 - don't have that paper, perhaps differences (anatomical?) are given there.
Biomphalaria - also in tanks? Who knows... That genus contains a lot of species.


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## miremonster (Mar 26, 2006)

Found a paper: http://www.academicjournals.org/article/article1380127419_Ibikounlé et al.pdf
As I've feared: extispicy...


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