Assassin snails

[mynameisnobody]

Hello all, I’ve noticed a tiny tick up in my snail population in my shrimpy 10 gallon. I was thinking of adding an assassin snail and then remove after a week or so. Do they predate on shrimp or do they only assassinate snails? 

[TheSwissAquarist]

Only snails in my experience; you’re safe.🙂

[SandBkeeper]

According to the internet, they could eat baby shrimp. However, I haven't seen it in my tanks and I'm pretty sure assassins would prefer the snails over the shrimp. 

[billango]

Sorry to add confusion and possible misinformation, but yesterday I found my assassin snail kissing one of my shrimp who I then found out was dead. I can't really confirm that the snail caused this death, but it kind of seemed like it to me because I had just added the snail in 2 days beforehand and hadn't seen any deaths prior. That being said, it is a small tank and wouldn't have been the hardest for the snail to get in contact with the shrimp compared to a larger setup; but even in my setup I think overall the shrimp population would still grow, even if it is the case that one gets picked off here and there. 

[lefty o]

any healthy shrimp wont be caught by an assassin snail.

[Lennie]

On 2/8/2023 at 5:38 PM, lefty o said:

any healthy shrimp wont be caught by an assassin snail.

I'm not sure about that one. In my experience, shrimp builds trust that cannot be broken. Mine don't have any survival instincts at this point istg. I can literally touch them, they don't get scared or act jumpy, but they are pretty healthy 😄 This building trust may take a long time tho.

I think if they know nobody is hurting them in that tank for a while, they are never scared of anything.

 

Also there are videos online about assasins predating on cherries. They are opportunistic carnivores. Maybe it is a last sort of option, but they clearly eat them if given a chance. But, assasins take meals and go for a nap for a while, So I feel like even if it goes to that route and eats a shrimp, probably the number would be super hard to notice.

I would worry about getting a female stored sperm in a store and letting her plant her bombs in the substrate and replacing your "pest snail" colony with assasin snail colony tbh. People generally forget how fast assasins reproduce too. And while "pest snails" are a part of a clean up crew, Assasin snails are just carnivore pets you gotta feed If you are not rehoming

[TOtrees]

This is one of those topics where you will always get a range of answers, those answers will span the full range from “it’ll be fine” to “disaster guaranteed”, and some folks will never change their minds. 

To the surprise of literally no one, I have an opinion. IMO it’ll be fine.

I keep assassins in many tanks with neos and I’ve never seen them kill or hunt them. They are very much carnivorous though, and also opportunistic. If a shrimp (baby or adult) isn’t fully healthy and isn’t able to get away like a normal healthy shrimp would, sure an assassin could probably capture it. 

[jwcarlson]

I'm not trying to hijack, but this seems relevant... how many snails (pest snail size) can an assassin snail eat in a day?  I ask because I would LOVE to get rid of the snails in my discus tank.  Elsewhere, I don't have as much concern about them.  But in my discus tank because I feed so heavily, I have a ton of them.  

As an example, this was in my HOB sponges and media, would not surprise me if this is only 1/3rd of the number that are in the media as it's impossible to get them all out.  And I clean this out about every 7-10 days.  I change water daily and I suck up at least 15-30 snails every day as well.  I crush all of them that I can, but I need something that will go in and do the dirty work of suppressing the population.  One of my concerns is that I feed the discus a lot of meaty foods like beefheart.  Are the assassins just going to eat that instead of eating snails?  I'm not *too* concerned about this because my removals seem to keep them relatively at bay.  I actually barely ever see a snail until I move driftwood to siphon every night (or doing filter weekly).  Thinking about buying five assassin snails and letting them loose.  Just worried that I'll be swapping one snail pest for another?  One of my main concerns is that they're going to get into the impeller and tear it up (the pest snails, not the assassin ones... just one of the reasons I'd like less of them).  

On the flip side, if I have a lot of assassin snails I would at least be able to give them away or something.  Maybe I just need a puffer.

 

Edited February 8, 2023 by jwcarlson

[Goldie Blue]

I have a lot of assassin snails in my community tank, with dozens of shrimp, and have no issues. Just keep them well fed, and they will leave them alone. They also share a tank with 3 nerites and leave them alone, though my nerites are huge. I actually see my shrimp and assassins eating together side by side all the time, no issues. 

[TOtrees]

On 2/8/2023 at 10:22 AM, jwcarlson said:

how many snails (pest snail size) can an assassin snail eat in a day?

I don’t know the answer to this, but I will say that controlling snail populations with assassins is a many-months process, not a matter of days or weeks. So I would assume their per-day consumption is on the low end. 

I’ve found that assassins prefer snails with no operculum (eg ramshorn > mts), but despite that they don’t seem to control pond snails well. Maybe the pond snails are just that much faster. I’ve also found that assassins prefer smaller snails over bigger ones, if there is a choice. 

If you’re starting with a booming prey population, remember they will be breeding regularly. So the prey population gets replenished as fast as predators can take them out. It’s not until the predator population ramps up to be proportional to the prey’s population/reproduction that you start to see the prey population really decline.  Eg you get way better control of pest snails after your assassins start breeding and their babies are at least half grown. That process takes 3-4 month, at least. 

[jwcarlson]

@TOtrees Yes, I understand all that. 🙂  My question was moreso out of curiosity.  I've seen assassin snails at the LFS, but they don't seem very big, so was just kind of thinking in my head how many snails they could possibly eat.  I don't expect to toss two of them in and have all the snails gone in a week. 🙂  I have thought about removing the fish and "nuking" the snails with something (whatever kills snails), but I'm sure that as maybe just as many draw backs as anything else.  

I know the root of the issue is the overfeeding in the tank.  I guess I'd hoped that nightly big water changes would keep them a bit more at bay than it has.  But like I said, I really don't see them hardly at all.  They hang out in the filter mostly, which may pose another issue as far as them getting hunted.

 

[TOtrees]

On 2/9/2023 at 11:05 AM, jwcarlson said:

I have thought about removing the fish and "nuking" the snails with something (whatever kills snails)

There’s something called Zap that’s basically copper in liquid form, that won’t harm (most) fish or plants, at least if used correctly. But it will kill any inverts like shrimps or “good” snails. Plus, if your tank is anything like mine, the biomass of snails is equal to or greater than that of fish, so if you kill all the snails… Big ammonia problem. 

[jwcarlson]

On 2/9/2023 at 11:49 AM, TOtrees said:

There’s something called Zap that’s basically copper in liquid form, that won’t harm (most) fish or plants, at least if used correctly. But it will kill any inverts like shrimps or “good” snails. Plus, if your tank is anything like mine, the biomass of snails is equal to or greater than that of fish, so if you kill all the snails… Big ammonia problem. 

I've been thinking about doing a wipe out, the rest of the tanks, I do not care.  But in the discus tank, for some reason, it's bugging me having hundreds (thousands?) of snails in the filter.  So yes, if I wipe them out it would be a pretty big ammonia spike.  I do 90% water changes every day, so I'm pretty confident I could manage through that.  My concern would be killing the discus inadvertently using something like that.  I'll have to do some digging.  I like having snails in my tanks, otherwise.  And maybe I'm blowing it all out of proportion.  It's just tough because of the overfeeding.

[TOtrees]

@jwcarlson In the tanks that are heavily fed, that inevitably have high snail numbers, I let the snails do their thing (reproduce and grow like crazy), and every few months I put in a trap, remove a few dozen, repeat a few times, and then... give them hugs and presents and send them to snail camp. The other option is to feed something like an algae pellet, which they love, and 30 mins later when the pellets are crawling with snails scoop them up in a net, and... give them hugs and presents...

These methods don't in any way eliminate the snail population, but it does keep the numbers low enough that my working tanks work like they're supposed to.