I posted the other week about some snails I had noticed in my relatively new tank; where I was warned that it would be wise to get the snail population under control while I can. Sure enough, the snail population has increased - not to the point where they're out of control - but if they continue to reproduce at the rate they have, I'd give it a few weeks before I've got myself a "problem".

I'm fairly positive that they're bladder snails, and I have since purchased two assassin snails in an attempt to keep their population under control - though these guys seem fairly chilled out so I'm not sure how helpful they've actually been so far (FYI, they've been in the tank for four days).

I've read time and time again about reducing the amount of food that you feed your fish, as "less food = fewer snails". However, I'm completely unsure of how much less I need to feed my fish to have an impact upon reducing my snail population. My fish supplier suggested to feed twice a day but I'm wondering if once a day may be more helpful to nip this in the bud? Or whether I should carry on feeding twice, and just use less food both times?

Additional info: I have 9 tetra, 3 guppies, 1 bristlenose catfish and 3 amano shrimp. I feed them twice a day (morning and evening), a combination of flakes for the tetra/guppies and pellets for the shrimp/catfish. Once or twice a week I will use a daphnia or an algae wafer alternative for example, to create a more varied diet. I remove any left-over food which is visible to me but I know there will be some which sinks into the gravel and slips through my radar. I siphon my gravel relatively regularly to remove this and there isn't a clear abundance of algae as of yet - but my snail population is still increasing?

I have come to the conclusion that the unseen food is the issue and that I need to reduce the amount I feed my fish to minimise this. And so, my question is:

How can I reduce the amount I feed my fish, to effectively minimise the reproduction of pest snails, without harming the fish?

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    This is a XY problem: Your asking two separate questions which are "Will reduce feeding keep my snail population under control" and "How to reduce feeding". Commented Sep 5, 2017 at 13:22
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    @KarlRichter I'll try to edit and rephrase my question.. I know that I want reduce the feeding - I see this solution cropping up time and time again - so I'm not trying to ask "Will reduce feeding keep my snail population under control?". I'm trying to ask how I can do this, in a way which will minimise further snail reproduction.. but without hurting my fish essentially.
    – Cthulhu
    Commented Sep 5, 2017 at 13:38

3 Answers 3


Feeding your fish once a day is good advice, but the result is this: you feed the fish (and the snails) less and so they will just reproduce slower. You could even stop feeding the fish for a week or a month and it would have no effect, except that your snails multiply slower and your fish will be starving (this is purely for an example and I would not recommend you do this).

The assassin snails will do the job, just be patient; ensure you have the right species of snail (Asiatic assassin snail).

Edit: a better source about assassin snails is this Wikipedia article.

I got my first fish tank in 1977 and have tried everything you can imagine, and the only really effective solution which I've found are the assassin snails.

When the assassin snails have removed the infestation, they will eat some of the fish food and could live for up to several years.

There is no need to feed your fish more than once a day or even once every two days.

Additional information: most snails are hermaphrodites (have both male and female reproductive organs), unlike the assassin snail. Assassin snails have separate genders and so, are less likely to cause an infestation of their species in your tank.

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    From my experience, it's unlikely that the assassin snails become a pest themselves. I also had a snail problem and added 3 assassin snails. At the peak of the infestation I once counted 9 assassin snails (and lots and lots of other snails). They usually hide, so probably I've had like 15 or more snails. Now I haven't seen any for a couple weeks/months, but my snail population is stable now. I see small snails, but no big ones. So there is still at least one assassin snail on the hunt. So these do stop breeding as soon as the food supply drops.
    – Diether
    Commented Sep 5, 2017 at 11:03
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    @ Diether I have spotted some assassin eggs nestled in my plants so perhaps this is a sign that they are hunting/eating pest snails.
    – Cthulhu
    Commented Sep 5, 2017 at 11:55

I wouldn't worry too much about bladder snails. They're pretty much as harmless as snails could be. They can't harm your living plants or any other animals in your tank and their population usually controls itself.

Instead they'll help keep your water clean and balanced. If there are indeed far too many of them for your liking, you're definitely overfeeding your fish. There should never be a problem for the snails starving your fish, because they're typically far more agile and faster picking up food.

Introducing predators such as assassin snails can help as well, just keep in mind "Who watches the Watchmen?", since assassin snails might also hunt slower fish and/or other animals besides other snails (depending on species).

As for the amount to feed: experiment with it. Your fish should be able to eat everything within a few minutes. If it takes significantly longer, like 30 minutes or more, it's certainly too much.

Keep in mind that fishes will just continue eating as long as there is food, even if they've had enough.

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    can you please back up the statement of asassin snails catching fish, i have never heard about this,even if asassin snails moves faster than other snails they are slow compared to fish. Commented Nov 29, 2017 at 8:53
  • Any flakes I put in disappear within a minute or so. However, I tend to leave any algae wafer I put in for the catfish/pellets I put in for my shrimp as it tends to take them a while to find it. Plus, my catfish only eats after I've turned the light off, which I do once I've finished feeding the other fish.
    – Cthulhu
    Commented Nov 29, 2017 at 9:33
  • @trondhansen Nope, only heard it myself including notes in some online shops selling snails.
    – Mario
    Commented Nov 29, 2017 at 11:49
  • @Cthulhu doesn't sound like over-feeding. Bladder snails can feed off algae alone as well.
    – Mario
    Commented Nov 29, 2017 at 11:50

You will starve the fish before the snails . I just crush the snails when I can conveniently reach them , the fish love it.

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    Bad idea. You're causing far more dirt and potential food for far more dangerous pests that way. Your tank can and will include species of planarians, which will love squashed snails.
    – Mario
    Commented Nov 29, 2017 at 6:34
  • So what I have done for 50 years won't work ? Commented Oct 24, 2020 at 14:13
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    Not saying it won't work, but it can cause other trouble.
    – Mario
    Commented Oct 25, 2020 at 6:11
  • The fish love the fresh meat and the calcium goes back into the water where it came from. Commented Oct 25, 2020 at 17:22

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