I've had an exclusive snail tank set up for several months, housing bladder snails, pond snails, MTS, and ramshorn snails. It has been going well up until this point.

Recently, I've noticed that their once long and flowing tentacles have started looking wrinkly, some of which have broken off and feature black spots at the ends. It generally starts at the tips, where they will start looking more twisted, wrinkly, and deformed before breaking off and leaving behind black spots.

This seems to have affected all snails with long tentacles, including the bladder snails and ramshorn snails. Aside from them being less active and spending more time in their shells, I have not seen any other signs of illness.

You can see the black tips in this image:

ramshorn tentacles with black tips

The only information I can find on tentacle damage is when other creatures in the tank bite them off-- Because this tank contains exclusively snails and the problem has only surfaced recently, it is very unlikely that this is the problem.

The tank is densely planted, and the water parameters check out fine.

What is this?

  • In one comment you write that you feed green beans to your snails. I honestly don't know anything about aquatic snails, but I do know that raw green beans contain hydrocyanic acid, aka hydrogen cyanide, which is very toxic to humans. Could it be that your snails are affected by this acid as well or a metabolic product of it? Cyanid compounds inhibit the cell's ability to metabolise oxygen, which often has the strongest impact in extremities with poor blood supply. But this is speculation, I don't know if snails react to green beans the same way humans do.
    – Elmy
    Sep 2, 2019 at 11:37
  • As far as I'm aware, it's a common food item for snails (I do boil them first as opposed to feeding them raw, so maybe that helps). In any case, I've got another tank of snails on the same diet, and they don't have this problem.
    – 560812508
    Sep 2, 2019 at 20:18

2 Answers 2


I have kept aquarium snails of different kinds but never encountered such an issue. I will still try to tell you as much as possible, in case anything can help.

Possible causes:

Water quality. This is the most easy answer. An excess of pollution could be burning up these sensitive parts. No matter what the issue is, keeping your water extra clean is your best bet, moreso until you know the exact problem and cause. I assume you know how to manage a fishtank and are aware of the nitrogen cycle.

Temperature of the water could be wrong. You can search online what temperature each snail prefers.

A parasite, fungus or disease. This seems very likely in your case, it looks like an epidemic. Maybe someone can recognize these symptoms and identify the issue. Then a medication could be recommended. I would suggest you bring one specimen or more to a specialist of snails if you can find any. Water quality will also help the healing.

A toxic chemical in the water. Did you add any chemical product recently to your water? New piece of decoration, new piece of filtration, a heater, new substrate, plants, anything? Think if you added something when this problem started. Snails are fragile when it comes to copper for exemple. It could be a paint on a piece of decoration.

Physical injury like you mentionned, fish attacks (you don't have fishes), or an uncovered filter intake or something, even some unwelcome invertebrate could be attacking them, but since it's spreading among your snails, this is probably not the cause.

Diet as Trond mentionned. Maybe they are missing something, either calcium or some vitamin. Besides sepia bone and vegetables, you could also give them actual fish food.

What you can do:

Keep the water clean, find a snail specialist or vet or hope someone here can diagnose what is happening.

You can try to separate healthy and not-healthy specimens with a second tank and see what happens. It might help you discover the root of the problem. You can restart a healthy population even with a few healthy individuals in a different tank. Be sure not to mix in water from the not-healthy tank, start it completely from scratch or from a healthy tank. Start as soon as possible to isolate healthy specimens before they catch it too. You can even put them in quarantine in glasses of water.

It might be better to focus on restarting a healthy colony rather than try to heal all the current snails, considering their reproduction rate.

Snails might easily regrow healthy tentacles once the issue is resolved.

I like your concept of a snail-only tank. Wish I could help more, very original question. Good luck.


The tentacles are sensory organs (chemosensory; they have two or four depending on type of snail): https://www.theanimalfiles.com/anatomy/aquatic_snail_anatomy.html

Some types of snails can have parasites but I am not sure this is the case in your snails.

You need to take a look at their diet to find the reason for the deformed tentacles and other damage to the body and shell. Be sure your snails get their need for calcium covered by adding a few seashells to your tank.

You can feed brussels sprouts and green vegetables or potatoes to your snails, but be sure to remove uneaten food if your snails do not want it (if your sails are still eating it just leave it in the tank until it is gone).

I buy frozen vegetables to feed my snails; by doing this i can feed the snails small portions so the water stays clean.


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