How to remove leeches from freshwater snails

How I removed leeches from Tylomenia snails.

Unfortunately I bought my orange Tylomelania snails and my yellow-black Tylomelania snail (maybe Tylomelania towutensis) infested with some small black leeches. Leeches are predators or ectoparasites. It depends on the size of a leech and on the size of a snail. So they are pests on snails and I wanted to remove them.

There exist an antiparasitic agent flubendazole, that can be applied against leeches (and also against planarians) in aquaria, but flubendazole would kill also all freshwater snails. Planorbella are the only known snails, that are nearly resistable to flubendazole. Flubendazole is insoluble in water and deadly concentration for snails will stay in aquarium for few months.

Behrendt & Lukhaup (2011) recommend to pick leeches up. I was checking snails and leeches for a week, but leeches were still on snail bodies. So I tried another plan. They can be very easily pick up from walls of aquarium, but they are crawling outside snail bodies very rarely.

I found no guideline how to do that and keep snails alive so I had to invent my own way.

At the website there are ways how to keep fish healthy. One of described methods uses alcohol for removing leeches from a body a fish. I decided to use the same method for snails.

I used toothpick with a cotton. I soaked it to a strong clean ethanol (about 70%-90%). I have put a snail out of water and I waited when the snail will stretch out.

It is necessary to put it to the water sometimes, but Tylomenia snails are quite resistant. My orange Tylomelania are smaller (shell height 40-45 mm) than yellow-black ones (shell height 61-64). Orange Tylomenia were stretching out of a shell more often and more extensively than those yellow black bigger ones. I think, that Tylomenia towutensis is afraid of any fast move in its surrounding and it is also at least partially afraid of light. It is more active during night in the aquarium. But maybe larger snail’s body is more difficult to manipulate out of water than smaller body. Therefore it is more difficult to remove leeches from larger Tylomenia snails.

When you will finally touch a leech with alcohol soaked cotton, the snail will hide inside its shell. Rarely a leech will stay on the cotton immediately. Usually the snail will create much mucus that will cover the dead leech. When the snail’s body will appear again, you can remove the dead leech covered with mucus quite easily with a brush or with pincers carefully. Anyway a drop of ethanol will kill a small leech immediately while a snail will survive.

It is time consuming method, but I do not know a better one. Moreover sometimes leeches are hidden under the snout or bellow tentacles and then it is impossible to remove them. The only way is to put a snail back to aquarium and to wait to another day when a leech will be on another part of the snail’s body.

Leeches are agile and they can move from a snail to another snail when snails are close to each other. Therefore it would be fine to keep healed snail from infested ones.

Orange Tylomelania with a leech on its head:

Tylomelania with a leechOrange Tylomelania with two leeches. There is also visible a snout and a genital groove:

Tylomelania with two leechesOrange Tylomelania with three leeches:

Tylomelania with three leechesLeeches can occur anywhere on the snail’s body:

Tylomelania with a leechDetail:

leech on a TylomelaniaLeeches are not clearly visible on other non-orange Tylomelania snails especially when there is detritus all around. There are two small leeches on a yellow-black Tylomelania (Tylomelania ? towutensis) – one under the right eye and one between right eye and the shell:

Tylomelania with leechesA leech on the snout under the right tentacle:

leech on a TylomelaniaLeeches also attacked Brotia pagodula. A leech on a head of Brotia pagodula: (dimensions of the shell 14.5 × 25 mm):


There is also visible an egg transfer groove on the Brotia pagodula:


I have verified that leeches comes from the aquarium pets salesman. So the species of a leech can be either some native Central European species or it can be any species from the source country of Tylomenia (Indonesia) or it can be any species transported by aquarium trade from anywhere in the world.

Dorsal view of an unidentified leech:


Ventral view of a leech:


Ventral view of a shrinked leech clearly shows its posterior sucker (on the right):


I stored leeches in ethanol for possibility of identification in the future.


(in Czech) Behrendt B. & Lukhaup C. 2011: Akvarijní plži. – Vašut, 64 pp., ISBN 9788072367481. From Geman original “Schnecken fürs Aquariumpage” (2009). page 27 and page 52. Treatment and Methodology. accessed 30 December 2013.

Wikipedia contributors. Flubendazole. Wikipedia. accessed 30 December 2013.


7 thoughts on “How to remove leeches from freshwater snails

  1. To kill snail leeches do this:
    • To test for snail leeches is simple ¼ teaspoon shrimp pellets will bring them out
    • First remove all plants.
    • Dip plant in a 50% hydrogen peroxide solution to dislodge pests by flushing with water
    • Save your plants in a bucket for 4 weeks
    • Remove all creatures which will die from salt being added, Rams horn, Pond snails
    • Snail leeches survive Clorox and all other solutions. I know I tried all suggested chemicals
    • Bring the salt level part- per-Thousand to 3 ppt with softener salt for 1 week
    • Lower it to 2 ppts for 2 weeks
    • The last week, do the above test.
    • If no leeches then change out with freshwater during this last week to 0 ppt salt.
    How this works is the apparently the leeches ball up in a protective cocoon and starve to death.

    • Thank you for this reply, and thank you also to Michal Maňas for this blog, very interesting! I realize this blog post is several years old by now but maybe someone is going to respond to me anyway.
      I have nerite snails, no Tylomenia, but they most definitely are plagued by snail leeches (not brown-reddish ones like in the picture above, but pale white or beige ones, max. 1cm long). I like the snails very much and would like to save as many as I can from the leeches, I feel very sorry that they are suffering in my care. Does anyone have experiences with the salt treatment on nerites, is it effective against the leeches, i.e. will the leeches either die from the salt after a while or crawl out of the snails? They are attached to my snails inside the snails’ shells, I only occasionally see a white ‘tail’ of a leech sticking out from under a shell.
      The owner of an aquarium shop who has a lot of experience with planaria, leeches and other aquarium pests actually mentioned a similar method with salt when I asked him for help. He suggested to slowly raise the salt level to about 5ppt over a few days so as to allow the nerites to get used to the salty water. He said while such a salt level will not kill the leeches, they are bothered by the salt and would crawl out of the snails after a while. I’m now at a salt level of 5ppt, since yesterday. For the most part the nerites don’t seem to be very affected by it, although they were more active at about 1-2ppt and some started to leave the water at times starting from a level of about 3ppt. They seemed to really enjoy a level of 1-2ppt. However, no leeches have come out of the snails’s shells yet, even though I absolutely know they are hiding in there and hurting my snails. The snails are displaying clear signs of suffering at times. I can see the leeches when the snails move on the glass walls of the aquarium and I shine a flashlight into their shells.
      Sadly I don’t think the alcohol-toothpick-method suggested in the blog post is not useful in my case as the leeches are inside the snails’ shells and simply won’t come out. Does anyone have any experiences with the salt method for leeches on nerites, suggestions, tipps? Do I simply need to wait for a few weeks?
      Thank you in advance, I appreciate anyone replying in support.

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