What's eating my snails?

PR Harbin · May 11, 2016

Hello, all - I am somewhat new to saltwater (~9 months since I set up my first tank - now I have 2...), and I'm running into an issue in both of my tanks. I keep snails of all varieties to help keep the tank clean (and because they're cool), but I often find snail shells empty, and I can't figure out what's eating them.

In my tank, I have a Foxface, Yellow and Blue Tang, Engineer goby, Resplendent Anthias, long nosed hawk fish, a few chromis, a few damsels, two clowns, a few pajama cardinals, a banggai cardinal, a bi-color blenny, and a fuzzy dwarf lion. I've also got several hermit crabs (also to keep the tank clean) and a spiny urchin. Any idea what might be doing in my snails?

thanks in advance for the insight!

Salty1962 · May 11, 2016

Are the snail shells broken? I can think of 2 things; 1- You don't have enough algae to keep them fed, 2- You have a Mantis shrimp in your tank. Are you loosing and of your hermits? That's what I'd look at to figure out why your loosing your livestock. Let us know how it works out!

larky · May 11, 2016

more than likely hermits. never again will i have hermets. they wiped out all my strombs. normally for food or to steal their shell

NeiDan · May 11, 2016

I'd bet on it being the hermits. They're ruthless. I like them, they're amusing to watch wonder around the tank, but they will attack snails or eachother with little provocation. I don't find it so bad that I would get rid of them completely, and they're very efficient at eating detritus and algae, but don't underestimate them.

PR Harbin · May 11, 2016

Snail shells aren't broken, and I regularly put seaweed under rocks to help keep them fed if the algae looks like it's getting low. It could be the hermits... there are plenty of empty shells they could use, but I guess that wouldn't stop them from attacking the snails...

Naiad · May 11, 2016

PR Harbin said:
Snail shells aren't broken, and I regularly put seaweed under rocks to help keep them fed if the algae looks like it's getting low. It could be the hermits... there are plenty of empty shells they could use, but I guess that wouldn't stop them from attacking the snails...

But it is THAT shell. Hermits are weird. Likely your culprit

nervousmonkey · May 11, 2016

Naiad said:
But it is THAT shell. Hermits are weird. Likely your culprit

Yeah, if you watch the hermits, they'll murder your snails. I've relegated my hermits to the sump. Can't have murderers in my tank

Roboson · May 11, 2016

What kind of hermits do you have? Certain kinds are more prone to killing snails.

ritter6788 · May 11, 2016

Hermits or whelks likely.

FL_Reefer · May 11, 2016

It's definitely the crabs, they love snails! That is why I no longer keep crabs in my tank

Roboson · May 11, 2016

Not all hermits eat snails. Only some hermits naturally prey on snails. However, if a hermit is starving to death, it will likely eat a snail. Depends on what kind you have.

FL_Reefer · May 11, 2016

That's usually what happens in my experience , start to starve and by by snails

Roboson · May 11, 2016

I mean anything would do that. With proper care, snails are in no danger from hermit crabs.

jetmaker · May 11, 2016

Don't rule out the long nose hawkfish

emilycoop · Nov 4, 2021

Someone just at my “nasirous” snail and a asteria! I have nothing in my tank but fish a clown goby, a conch and tiny stripped brittle stars!! I have never had a hermit in this tank or anything aggressive! I’m also missing my goby but he could just be hiding good but he’s not eating. But that’s all I have in the 15gallon water-box! What is going on! Two dead snails in two days with completely empty shells.

Tbg299 · Nov 4, 2021

PR Harbin said:
Hello, all - I am somewhat new to saltwater (~9 months since I set up my first tank - now I have 2...), and I'm running into an issue in both of my tanks. I keep snails of all varieties to help keep the tank clean (and because they're cool), but I often find snail shells empty, and I can't figure out what's eating them.

In my tank, I have a Foxface, Yellow and Blue Tang, Engineer goby, Resplendent Anthias, long nosed hawk fish, a few chromis, a few damsels, two clowns, a few pajama cardinals, a banggai cardinal, a bi-color blenny, and a fuzzy dwarf lion. I've also got several hermit crabs (also to keep the tank clean) and a spiny urchin. Any idea what might be doing in my snails?

thanks in advance for the insight!

Have you ever heard any clicking noises coming from your tank at night? Many small snails were dying in my tank. It turned out I had a mantis shrimp hitchhike in from some live rock and didn't see it for 3 months.

rhostam · Oct 5, 2022

OP, I realize this is an old thread, but did you ever find out what was eating your snails?

I have gone through hundreds of snails of all sizes (up to 1.5”) and species. Today I notice now my starfish has two arms that appear to have been bitten off.

I have tried sequestering the largest of my hermits to sump and I still had snails dieing and being eaten.

Has anyone had high phosphates kill off their snails? I’ve been battling that for months now and until recently made very little headway. If they’re dying to high PO4, then I could understand hermits eating the body.

Not sure hermits would harm a sand sifting starfish, though…

I looked the other day and noticed a single super tiny worm. Even with a 6” magnifying glass it looks like maybe a two inch super slender millipede. I understand if there is one is probably more. I couldn’t get a picture though. It looked red to me. I don’t see signs of a larger burrowing creatures. But I’m now considering such a culprit as well. I also haven’t had any fish casualties and some of them sleep quite low in caves towards the bottom of the tank.

ISpeakForTheSeas · Oct 5, 2022

rhostam said:
OP, I realize this is an old thread, but did you ever find out what was eating your snails?

I have gone through hundreds of snails of all sizes (up to 1.5”) and species. Today I notice now my starfish has two arms that appear to have been bitten off.

I have tried sequestering the largest of my hermits to sump and I still had snails dieing and being eaten.

Has anyone had high phosphates kill off their snails? I’ve been battling that for months now and until recently made very little headway. If they’re dying to high PO4, then I could understand hermits eating the body.

Not sure hermits would harm a sand sifting starfish, though…

I looked the other day and noticed a single super tiny worm. Even with a 6” magnifying glass it looks like maybe a two inch super slender millipede. I understand if there is one is probably more. I couldn’t get a picture though. It looked red to me. I don’t see signs of a larger burrowing creatures. But I’m now considering such a culprit as well. I also haven’t had any fish casualties and some of them sleep quite low in caves towards the bottom of the tank.

Out of curiosity, do you have any pictures of the starfish with its injuries, and what kinds of snails have you been losing?

rhostam · Oct 6, 2022

ISpeakForTheSeas said:
Out of curiosity, do you have any pictures of the starfish with its injuries, and what kinds of snails have you been losing?

I’ll take a pic in the morning. I’ve lost Mexican turbos, zebra turbos. margarita, and nauseous snails. So far only the largest of the zebra seem to survive (2”+). Even most most long held Mexican turbos have succumb. The smaller snails (1/8-1/2”) seem left undisturbed on the whole. This is what led me to think the hermits were the culprit as several of them have grow quite large. But I kept losing snails even after all of the hermits were in the sump for a few weeks.