Last Updated: 2/9/16

Effects of Water Hardness on Snails' Shells
Algae on Snail Shells
Fungus on Snails
Snail Parasites

Snails require calcium, magnesium, and other minerals to grow and maintain their shells. If their water is too acidic and/or soft, their shells may begin to dissolve. If you see snails with holes in their shells, the water's hardness is too low (it is soft). Aquarium stores sell chemicals to increase the water's hardness. Those with calcium can be added to help snails in soft water. Ramshorn snails are said to be most effected by too soft water while Malaysian trumpet snails usually fare better. My tanks have mini ramshorn snails that do okay, and my tank is as soft as they come! To increase the hardness of an aquarium or pond gradually and continually, oyster shells (sold for chickens, etc. at a farm feed store), crushed coral gravel (sold for marine tanks), or cuttle bones (sold for caged birds) may be added in small amounts. They can be put in with the substrate/gravel on the bottom, contained in a bag in the tank/pond, or put in a bag in the filter (I think that works best as water moves over them continuously). The "bags" can be mesh filter bags now sold for aquariums (at least That Pet Place and Drs. Foster and Smith sell them), pantyhose legs, or even fine mesh laundry bags. These will all leach calcium over time into the water. I put bags of oyster shell in my pond filter. For more information on hardness, alkalinity, and other water chemistry, see my water chemistry page. Here is a photo of one of the mesh filter bags:

I have gotten a number of questions about algae-covered snails. It is perfectly normal for algae (and other microlife) to grow on the shells of snails. It is more likely to occur in aquariums or ponds that have a lot of algae, light, and nutrients. The algae provides some camouflage for the snails and does not normally harm the snail. If there is a lot of algae, it may slow down the snail. Using general algae control methods (lots of plants, shade, good bacteria, good filtration, barley straw, etc.) should reduce the algae growth. The addition of more snails, preferably small ones, may help as the small snails can eat the algae off of larger snails. If someone really wants to reduce the algae on a snail's shell, they can use a toothbrush to gently remove most of it. Do not over scrub. It is best to use a dedicated aquarium/pond only toothbrush for this task. For more on algae, visit my aquarium algae and pond algae pages.

Snails sometimes grow fungus on their shells, especially if they are cracked. Try using a toothbrush to remove it as in the section on algae on snail shells. Some fungal medications may kill snails but they can be tried as a last resort. PimaFix by Aquarium Pharmaceuticals may be a better option to try as it is all natural. Here is a photo of it (the link no longer works):

On 8/15/07, Bambi had this to share (edited by me, added notes in brackets):
"I write you today to share my experience curing my gold mystery snail of a fungus. Last year, I got a betta which was my first pet fish since childhood. I also got a gold mystery snail. Due to ignorance (my bad), I let the tank get too dirty, and they both got fungus. After I improved their conditions, the fish got better but the snail still had a white sweater growing on its shell, and, to make matters worse, the shell was cracked from a fall. The people at the local shop said that you can't really treat a snail for fungus because the snail is so like fungus that anything that kills fungus will kill the snail [Note from Robyn: A snail is nothing like fungus but fungal medications often kill snails.]. I looked on the internet and saw nothing. I gently cleaned the snail with a toothbrush but the sweater kept growing back. I decided to try a very diluted solution of [hydrogen] peroxide and water. I had read that [hydrogen] peroxide kills snails so I used very little. I cleaned the snail with the toothbrush, then I rinsed the snail's shell with a mix of about a capful of [hydrogen] peroxide to a cup of water. After rinsing with [hydrogen] peroxide, I immediately rinsed the snail with water. I did this a few times. After the first treatment, the sweater only grew back in the very front of the shell which is the area I had avoided so as not to burn the snail. I repeated the treatment a second time but this time a let some get under the rim. I was worried about burning the snail but the fungus was life-threatening as well from what I was told so I figured it was justified. Fortunately, the snail seemed fine right away, and the white sweater never came back. The cracks in the shell have healed as well, but it looks like it has suffered a few holes elsewhere. I've been feeding it spinach and some eggshell, and the shell is healing...." [Note from Robyn: Try this treatment at your (or rather the snail's) own risk. I thought I would add it here as it is an option to try.]

On 2/7/16, Sue sent me an e-mail in regards to the message from Bambi. I am including both because the information may educate others. I could just delete Bambi's post above but if someone is looking for information about this, these two messages may provide some insight.
"Thanks for your very informative website which has given me a lot of great information. But I thought I'd drop you a line about the anecdote from Bambi under Aquatic Snail Health/Fungas on snails regarding using hydrogen peroxide. I searched the internet for treatment of snail fungal infections, found this, tried it and it was FATAL IMMEDIATELY. I think, because most kitchens or bathrooms have a bottle of hydrogen peroxide on hand, many people will try it in the absence of Pimafix or Melafix, because they feel time is of the essence. This comment was the only one I could find on the internet about treating snail fungal infections with hydrogen peroxide, so there weren't any other thoughts or opinions (or opposition - I wish there were, I'd never have tried it). But I would respectfully suggest that it should be deleted, as it was toxic and fatal within minutes. I'm so angry with myself for being so stupid in trying it. OF COURSE hydrogen peroxide is going to be fatal to a tiny snail body. If it wasn't in her case, I can only assume the peroxide was so degraded as to be fairly inert. But I wonder how many others have followed this advice with disastrous consequences, not to mention a hideous death for the poor snail. Anyway, thought I should let you know its probably not a good thing to include in your website."

Like basically all animals, snails can get and carry parasites. Also like most animals, those parasites tend to be specific to that group of animals. In other words, most snail parasites are not contagious to fish or other animals. There are some parasites that do use snails during part of their existence and fish during another part of their existence. An example is the flatworm Bolbophorus confusus. See this link for more on that.

So, there may be concern regarding snail parasites both for the sake of the snails and for the sake of fish with the snails. Unfortunately, the chemicals that kill most parasites also kill snails. If your concern is the fish, then using copper sulfate to kill all the snails may help break the parasite's cycle. If you are worried about the snail, I am not sure what to do. If anyone has ideas, please contact me. It seems flukes and leeches are the most common parasites of snails. I found this link:
Leech predation on snails

On 8/29/07, Anita in Hungary sent me these photos of her big snails with apparent parasites. They might be flukes or perhaps leeches. I do not know the species of snail or apparent parasite. She calls the snails "wandering snails." She circled the flukes.
Fluke on snail
Fluke on snail
Fluke on snail
Fluke on snail

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