Cecil

Snails in system driving me nuts

23 posts in this topic

I have one RAS that got inoculated with snails by accident from a pond and they live in the moving bed filter with the veligers apparently moving into the fish tank itself. In no time they cover the tank walls by the hundreds if there are no fish in the system yet, or there is a species that is not interested in feeding on them. I've noticed it's easy to spread them with equipment also.

If I have yellow perch (Perca flavescens) , bluegill (Lepomis macrochirus) or blue tilapia (Oreochromis aureus) in the system they snap up the snails as soon as they appear on the tank walls. Presently I have black crappie in the system and they have no interest in consuming the snails. 

I think adding some of the other species to the crappie tank would fix the problem but I don't have any of those presently available of the same size. 

Does anyone know of a treatment that I can make that would not harm the biofilter but will kill the snails and their veligers? 

Perhaps I need to source someone with small tilapia of about 3 inches. I can easily order them and have them shipped but shipping is expensive for the few I need. And the closest supplier is at least an hour and a half away. 

I actually have tilapia at 2 high schools but they are so large I believe they would consume the crappie. I could hatch some eggs but have no place to do it in, nor the time presently. 

 

 

 

 

Edited by Cecil (see edit history)

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When I had a snail population my tilapia couldn't be less interested.  The snails were everywhere.  My solution was to get some assassin snails from the pet store.  No chemicals, no unintended consequences , eventually no snails clogging everything.  I forgot about the problem and I think the assassin's eventually starved, which I'm not particularly happy about.  

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I haven't had time to get the full gist of this post but the mention of snails pricked my interest.  

If I recall correctly, UVI used 'redear sunfish' or something similar....but I don't what snails they had (or, for that matter, what snails you have)....and they're in a warmer climate.

If your snails are like the little white water snails that I've seen in aquaponics systems, they will eventually block pipework, seize your pumps and generally give you a very bad time.

These things will devastate a system.

My response to this threat would be to drain the system.....and dismantle it sufficiently to be able to clean it as much as practicable....and to declare it dry.  Then I'd leave it for at least a week.  After that. I'd flood the system to the point where all surfaces are wet.....and add some sodium hypochlorite and recirculate that for several more days.

I'd love to be able to use something like assassin snails but I don't believe we have them here....and unless there's a local equivalent...it would probably stay that way.

I think the most direct solution is to shut the unit down and clean and disinfect it thoroughly.  The white snails to which I referred earlier, breed so prolifically that they just jam the system up...quite literally....and once their numbers mount, it happens very quickly.

Gary

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Our Seabass  (barramundi) devour the apple snails.  We breed those snails in a separate tank and feed them live in batches.  I think they would eat all kinds of snails.

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On December 12, 2016 at 6:25 AM, GaryD said:

I haven't had time to get the full gist of this post but the mention of snails pricked my interest.  

If I recall correctly, UVI used 'redear sunfish' or something similar....but I don't what snails they had (or, for that matter, what snails you have)....and they're in a warmer climate.

If your snails are like the little white water snails that I've seen in aquaponics systems, they will eventually block pipework, seize your pumps and generally give you a very bad time.

These things will devastate a system.

My response to this threat would be to drain the system.....and dismantle it sufficiently to be able to clean it as much as practicable....and to declare it dry.  Then I'd leave it for at least a week.  After that. I'd flood the system to the point where all surfaces are wet.....and add some sodium hypochlorite and recirculate that for several more days.

I'd love to be able to use something like assassin snails but I don't believe we have them here....and unless there's a local equivalent...it would probably stay that way.

I think the most direct solution is to shut the unit down and clean and disinfect it thoroughly.  The white snails to which I referred earlier, breed so prolifically that they just jam the system up...quite literally....and once their numbers mount, it happens very quickly.

Gary

Draining is not an option as I have no place to put the fish. 

I maybe O.K. as far as pumps as I use only one small mag drive pump for the system and it has a sponge filter on it to keep out snails large enough to damage it. 

I may have to check a local pet store for assassin snails as the fish I could add my own fish buy they are either too large to not available to me this time of year with the ponds frozen over. It's 8 degrees F. here right now. 

Edited by Cecil (see edit history)

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Going to pick up a dozen assassin snails from a local pet shop next Thursday. Thank you for the suggestion Aufin! 

 

 

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On December 12, 2016 at 10:02 AM, vkn said:

Our Seabass  (barramundi) devour the apple snails.  We breed those snails in a separate tank and feed them live in batches.  I think they would eat all kinds of snails.

Vkn,

That's cool. Like I said I usually have other species on hand that would do that same but not at the moment.  The nearest place I know of that rears barramunid is in the state of Massachusetts USA which is about 800 miles away. And I doubt the outcome would be good putting them in with the crappies (Pomoxis genus). 

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On December 10, 2016 at 9:02 AM, Aufin said:

When I had a snail population my tilapia couldn't be less interested.  The snails were everywhere.  My solution was to get some assassin snails from the pet store.  No chemicals, no unintended consequences , eventually no snails clogging everything.  I forgot about the problem and I think the assassin's eventually starved, which I'm not particularly happy about.  

Which species of tilapia were you using? Mine were blues (Oreochromis aureus) and within a short time of putting1 inch fingerlings in the tank, from an overnight shipment, they were nailing the minute snails from the tank wall. A regular feeding frenzy. I got the tilapia from the site sponsor Allied Aqua. 

Edited by Cecil (see edit history)

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yah all of my systems have small pond snails. I am sure it came in when i bought fish from a pond stocking place and they are prolific.  I cant keep them out of the plumbing and the filters but at least once a year i will put some red ears in each tank and they  will annihilate all traces of snails in that tank. in my experience bluegill and tilapia also eat snails but they are more opportunistic as i dont think they can just crush a snail on a wall from behind like a RES can. 

 

Personally, i dont get worked up about the ebbs and flows of the snail population. In 3-4 years i havent really had any huge issues, just periodical RES control. I do think it causes extra wear and tear on my water pumps . I do try to filter the big snail shells and such from going through the pump, but i do not doubt i am getting less pump life because of this.

On the other hand they do seem to do a decent job of controlling surface algae and they seem to feed on solid sediment if some settles in the bottom of the fish tank, in a filter or in a grow bed, they seem to have a place in an ecosystem. They just need to still be a part of the food chain to keep them in balance.

I know that doesnt help you cecil, just diatribing a bit of empathy i suppose.

 

How does the assassin snails work? What do they do once they control your snail population? Do they leave your system? Are you trading one nuisance for another? swallow the bird to catch the spider to catch the fly?

 

 

 

Edited by bcotton (see edit history)
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2 hours ago, bcotton said:

 

How does the assassin snails work? What do they do once they control your snail population? Do they leave your system? Are you trading one nuisance for another? swallow the bird to catch the spider to catch the fly?

 

All I know about the assassins is what I found on Google.  Seems they just cruise around looking for dinner, preferably an unsuspecting snail.  Whether they're hunters or just opportunists, I couldn't say.  The assassins are in the welk family   What the difference is, again,.....don't know.  What I do know is after putting up with snails clogging everything for way too long, the assassin's seem to have done a fine job of making snails extinct in my little part of the cosmos.  I'm expecting they starved to death since, I'm not very happy to admit, I forgot about them.  I remember reading they can be fed a small piece of raw meat occasionally if I wanted to keep them healthy.  My original plan was to give them back to the pet store when they were done.  

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Hi

I know you don't normally eat your trouts so taste or off-flavours is not relevant.

Maybe you get so many, now that you hatch them, that some of the culls, might find the way to the table as a byproduct ?

If so the snails could be seen as a positve thing(workers like scud) in the filters, aslong as they don't clog pump/pipes

         CONTROL OF GEOSMIN AND MIB (2)BIOLOGICAL METHOD:SNAILS GRAZING ON BIOFILM Can snails reduce TOC in RAS?
                    Davidson and coworkers at Freshwater Institute, Shepherdstown: 500 l experimental tanks with 30 rainbow trouts (111 g)
Streptomycete bacteria found in biofilm on walls in aeration sum Freshwater snail Physa gyrina living in aeration sump removed biofilm.
Snails reduced density of streptomycete bacteria by 3 fold in the biofilm Few streptomycetes in the water.
from 150,000 to 50,000 streptomycetes per 100 ml biosolids
 
 
cheers
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Ande,

 

So far no snails in the trout RAS as I've been trying not to mix equipment etc. It's the crappie (Pomoxis nigrogmaculatus) tank where the snails are. I also completely sterilized the cold water system before I cranked it up. 

Interestingly the trout most certainly do eat snails as I have found them in the stomachs of the ones I did not sell, and they aren't very common in the trout pond vs. some of the other ponds. I wouldn't doubt if the fed on then during the winter when I'm not feeding them. 

Once read about a strain of brown trout in Ireland called the Gilaroo that feed exclusively on snails. This particular strain of brown trout has brilliant read spots. 

O.K. here they are:

https://en.wikipedia.org/wiki/Gillaroo

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Hi Cecil

I just posted this in the dowload section with your Hatch/trout ras in mind, It's a nice read IMO

cheers

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Wow Ande that quite the reading. Very good material!

What do you think about the regulations and control of aquaculture in your country? Too much or just right? 

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Hi C

On 17.12.2016 at 4:18 AM, Cecil said:

Wow Ande that quite the reading. Very good material!

What do you think about the regulations and control of aquaculture in your country? Too much or just right? 

I'm fairly fond of the regulations as of today, I do think they are "a bit" to strict on "small" landbased operators, more spesifically the mandatory demand on formal degrees or education(to be in charge) to run a operation.

IMO this makes it extremly difficult(expencive) to start a new small aq operation, as part of a smallholding, but I belive there is a positive change comming here soon.

I think it's great that our politicians across the board (left/right/green) have mutual ambitions, to hold and/or expand our posistion, within aquaculture in a 50 year horizont, I wish politicians would/could have/hold such long term visions, on other matters as well

cheers

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On 13/12/2016 at 2:02 AM, vkn said:

Our Seabass  (barramundi) devour the apple snails.  We breed those snails in a separate tank and feed them live in batches.  I think they would eat all kinds of snails.

Hi VKN you really caught my attention, as I am doing a project with barramundi at the moment.

Do the barramundi eat the snail complete with the shell?? or do they de-shell them out first? Do you dump the snails in the tank or how do you feed them?

How big do you grow the snails? and how long does this take you?

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On 16/12/2016 at 8:27 PM, ande said:

Hi

I know you don't normally eat your trouts so taste or off-flavours is not relevant.

Maybe you get so many, now that you hatch them, that some of the culls, might find the way to the table as a byproduct ?

If so the snails could be seen as a positve thing(workers like scud) in the filters, aslong as they don't clog pump/pipes

         CONTROL OF GEOSMIN AND MIB (2)BIOLOGICAL METHOD:SNAILS GRAZING ON BIOFILM Can snails reduce TOC in RAS?
                    Davidson and coworkers at Freshwater Institute, Shepherdstown: 500 l experimental tanks with 30 rainbow trouts (111 g)
Streptomycete bacteria found in biofilm on walls in aeration sum Freshwater snail Physa gyrina living in aeration sump removed biofilm.
Snails reduced density of streptomycete bacteria by 3 fold in the biofilm Few streptomycetes in the water.
from 150,000 to 50,000 streptomycetes per 100 ml biosolids
 
 
cheers

This is another good find Ande !!! The aquaculture industry is working hard on reducing off-flavours coursed by Geosmin & MIB. Especially for fatty slow growing warm water fish species this is a big problem (like the aussi murray cod), as 1 week purging is often not enough.

Although practically I am not sure how tight snail population control is possible in RAS.

btw would be interesting to know if the plants in a aquaponic system have any impact on the build-up of off-flavour compounds in the fish tissue.

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Speaking of off flavor I wonder if nitrates could have anything to do with it? I say this because the best tasting fish I ever ate were tilapia grown out in an aquaponics system where plants kept the nitrates at bay. I've eaten store bought tilapia that had an off flavor. 

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Nitrates shouldn't influence off flavor as they don't accumulate in the fish, and by them-self probably have no flavor for us.

I ate cod coming from water with nitrates of 1500 mg/l, and they were delicious (my wife cooked them and she's a professional chef ;) )

These off flavor compounds are accumulating in the fish (mainly in the fat) and some people have a very low threshold for them. In contrast some people are relative insensitive and are fine with completely unpurged fish.  btw this problem is not only happening in aquaculture as some wild fish has the same issues. 

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On 12/24/2016 at 5:26 AM, phri said:

Hi VKN you really caught my attention, as I am doing a project with barramundi at the moment.

Do the barramundi eat the snail complete with the shell?? or do they de-shell them out first? Do you dump the snails in the tank or how do you feed them?

How big do you grow the snails? and how long does this take you?

Oops.. almost a month went by and phri, sorry I missed replying to your questions.  Hope it is not too late.

I have seen seabass eating some apple snails in complete.  I also used to collect the floating abandoned  shells.  So I think both happens.  We used to dump the snails directly in the fish tank when we were in a hurry but IMO the best practice is to boil, de-shell the snails, and feed.

They grow to harvestable size in about 3 months, 45-60 snails per kg.

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Thanks VKN,

No it's not to late, I might try to run a feeding trial with snails for barramundi. So this are apple snails, which you grow on plants? Do you just feed some of these every day? any idea on impact?

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