FAQs on Control of Snails in Freshwater
Aquariums by Baiting/Removal
Related Articles: Snails
and Freshwater Aquariums by Bob Fenner, In vertebrates for
Freshwater Aquariums by Neale Monks, Fresh and Brackish Water Nerites by Neale
Monks, Assassin Snails and
Sulawesi Elephant Snails. Keeping Clea and Tylomelania in the
Aquarium by Neale Monks,
Related FAQs: Freshwater Snail Compatibility &
Control,, Freshwater Snails 1,
Freshwater Snail Identification,
Freshwater Snail Behavior,
Freshwater Snail Selection,
Freshwater Snail Systems,
Freshwater Snail Feeding,
Freshwater Snail Disease,
Freshwater Snail Reproduction,
Snails by Species: Mystery Snails, Apple/Baseball Snails,
A shallow tray, dish... with sinking pellet,
Picking off leaves w/ eggs, scraping same from
sides of the tank and siphoning out
Freshwater Snails Overtaking My Tank
I have searched your site to try to find out the best way to rid my 20
gallon freshwater quarantine tank from snails.
<If it's a QT tank, then manual approach will work best. Strip
the tank down, clean the tank, deep clean or replace the gravel, and
that should be that.>
I received quite a few plants from someone and knew from past
experiences that they would most likely have snails within the
<Can be the case; use a potassium permanganate dip. Take care not
expose the plants for too long though, as snail-killing potions are
harmful to plants.>
I set up a tank only for the plants so I can monitor them for a month
or two to see if my suspicions were correct, and guess what, I was
right. Now since there are no fish, I have been leaving the tank alone,
with only co2 and some dechlorinator when I do a water change, roughly
once a month hoping they would die from lack of food.
<The bigger problem is that the filter bacteria will die without a
source of ammonia. So to a degree, the snails are helpful here, since
they eat food and excrete ammonia.>
They don't seem to me eating my plants (I don't have any idea
what types of plants or snails I have) but they eggs must have hatched
recently. I have a good 50 babies latched onto glass, leaves, roots,
etc. there is no gravel or decoration in the tank. Strictly plants.
<Dip the plants, siphon the remaining snails from the tank, and then
return the plants.>
I just bought one of those cheesy snail catchers but I know that
doesn't work very well and liquid snail killer is also a plant
<Not if used for short periods, typically a 20-minute dip.>
I was squishing them but they are just too many snails with too many
hiding spots. What should I do? If I continue to not feed, will they
all just eventually die?
<Population size is certainly related to food availability, so
eventually yes, population will drop to that supported by ambient
Some of the leave seem to be dying off which is causing some debris at
Should I give it a good cleaning to get it all out of the bottom so the
snails have nothing to feed off of?
<If you want.>
Thank you for your time.
<Snails aren't really a big deal, so I tend to ignore them. Clea
helena is a good snail-eating snail, and breeds quite slowly, so adding
a few of these will control most snail populations nicely. Otherwise in
themselves snails do little harm, barring a few species that eat
plants. Cheers, Neale.>
Re: Freshwater Snails Overtaking My Tank 6/1/10
Thank you for your reply Neale. Most people don't mind snails but I
am one of the few that will do everything I can to avoid them.
<I see. Well, you're probably wasting your time here.>
I don't like them climbing everywhere and they multiply too fast
which makes aquarium maintenance more work that I need.
<On the contrary, snails can be very useful for keeping aquaria
Melanoides sp snails, the ones often called MTS or Malayan Livebearing
Snail are the equivalent of earthworms, burrowing through the substrate
removing organic matter and aerating the substrate. Now, can you have
many of them? Sure. But when that happens it's a result of chronic
overfeeding and/or under-cleaning of the substrate. Think about it:
these snails need food to grow and breed. No food, no baby snails.
It's like finding cockroaches in the kitchen, and blaming them for
making the kitchen messy. No, the cockroaches are there precisely
because a messy kitchen has lots of food for them.>
I am glad you mentioned the potassium permanganate but I have been
unable to find this within any US Fish supplier. I found that Jungle
brand liquid Water Clear has potassium permanganate in it but have not
been able to buy it since only the tablets are what seem to be common.
There is nothing to tell me if the tablets have the same active
ingredient. Can you please point me in the right direction?
<Potassium permanganate is fairly toxic, so should be used with
care. When dipping new plants, immerse them in a dilute "rose
wine" coloured solution for 5-10 minutes. Rinse off the plants
before putting them in the aquarium.
There's no real way to kill snails in an aquarium without risking
the lives of your fish and plants. So ultimately snail control comes
down to [a] keeping them out; [b] minimising waste food so snail
populations cannot grow rapidly; and [c] stocking some type of
Last Check before First Trip, FW snails 5/11/10
Please help bring a couple things together that I understand in general
but am not sure on my specifics.
As a recap, in addition to four species of fish, I added four zebra
Nerite snails to help with algae control and found a "baby"
hitchhiker. Well, now I've found two more. Still to small to get a
good pic of but they are growing very fast and I hope to God there are
no more. I'm still baffled as to how they got there since I hand
placed the much larger zebras by hand so they were upside up in the
tank. I'm not sure the environment can handle a total of seven at
<They aren't Nerites, I'm sure. Much more like Physa or
They also don't look like zebras at least at this point. More like
apple or at least more cochlear. They are hard workers mostly clinging
to fake plants but they are on the move just like their larger
<I have Physa in planted tanks and they don't do any harm that I
I'm not talking about his because I am some proud parent pleased to
have more wildlife. Just the opposite, I'm looking for balance and
have had enough problems with getting ammonia under control.
Is it possible that having a large crew of snails working fast on a
tank will create ammonia that wouldn't otherwise be there?
In other words, scraping algae doesn't create ammonia
<Yes it does.>
but having a snail eat and poop it does.
<Protein becomes ammonia, whether fish food, rotting vegetation, or
baby snails. Just because algae and plant material contains a lower
percentage of protein than animal material, it doesn't mean
it's protein-free. Put another way, snails consume plant material,
and appropriate the nitrogen in the plant material into their own
tissues. They don't make protein from nowhere.>
I still like this better than scraping and honest the snails are
extremely fascinating to watch and ponder the Creators intentions.
The main question is, I know already that fish can go a bit without
eating and that has a benefit of reducing ammonia from being increased
over a few days.
I will be leaving town this upcoming Saturday at around 4pm and
returning the following Thursday around 2pm.
<They don't need feeding for this short period. If you feel the
need, leave a slice or two of cucumber or a piece of lettuce, and
they'll nibble on that.>
What is your recommendation for me specifically please? I want to do a
water change and would like to know what percent you recommend for this
scenario and what to do about feeding. I know three days is OK but five
seems pushing it. Would a two day weekend feeder be a good idea to
bridge the absence of feeding to only be three or should I put in a
veggie slice or what?
<Skip the feeding block option; minimal benefit and they can mess up
water chemistry as they dissolve.>
I'm sorry to bug you about something so specific, I wouldn't
consider feeding them if it was three days, but with the ammonia issue
in the back of my mind I'd like to maximize survival the best as I
can. Haven't lost anyone yet.
And finally, what to do with these small snails and when to do it.
Perhaps return them to the LFS when they are a big larger or are these
tiny animals enough of a threat to this trip that they should be pulled
out before then.
<Manual removal of the adults should prevent further generations.
Otherwise let your Clea helena eat them, if you have some.>
Re: Last Check before First Trip 5/11/10
Thank you for the ID on the snails. They do look like Physa but there
are no adults.
<Eggs are common on plants.>
Well, I guess I shouldn't say that since I never heard of this
species until 10 minutes ago.
<Well there you go.>
More reading to do! Unless they hitched inside the closed shells of the
Nerites then it's either the snail fairy or both myself and the LFS
need new glasses.
Should I do an extra percentage of water change? 20%? 40%?
<Just do a regular water change. No need to complicate things.
Re: Last Check before First Trip 5/11/10
Neale, if you see this before replying to the last one. Is this species
of snail a nuisance?
<Physa spp. you mean?>
I mean is this a typical hitchhiker that one would otherwise not buy or
want in the tank on purpose? So far I see that they are fast
<They may eat soft and tender plants, but I've never found them
to be a particular problem. They prefer algae, and most of the time my
specimens are either on the glass or on top of the floating plants. I
consider them pretty harmless, but then I do have Clea helena, puffers,
Synodontis or loaches in the tanks with them, so their populations are
bound to be kept in check somewhat. Cheers, Neale.>
Snails, FW, control 7/31/09
I have a number of small snails in my 20 gallon tank. They came in on a
live plant and have multiplied like rabbits. I must admit they do seem
to keep the tank clean. Is there an effective way to keep the
population of snails in check? I'd like to have some, but not
dozens and dozens.
<Snail populations grow fastest in tanks with lots or organic
debris, so one way to control their population is to keep the tank (and
the filter media) as clean as possible. Manually removing snails is an
with various DIY traps described in books and web sites. JBL
manufacture a device called the LimCollect that could be used
if you want a commercial product. None of these traps works
particularly well, and you have to use them night after night to have
any hope of reducing a snail population.
Snail-killing potions should be avoided as these usually do more harm
than good: a bunch of dead, rotting snails will do far more damage to
your water quality than they would alive! My favourite way to control
snails is to add a few Clea helena. These are snail-eating snails that,
over time, have a remarkable impact on populations, removing most of
the snails smaller than they are, so only a few larger ones survive.
Snails and Duckweed: FW Snail and Duckweed Control.
Also Plant health. 7/23/2009
First, I can only restate what so many others have said before -
your website is awesome and absolutely my favorite browsing spot.
Thank you again for all your hard work!
<Thank you for the kind words.>
I live in fear of repeating a silly question you have answered a
thousand times before... but I cannot seem to find clear answers
myself. Here goes...
I have a 30gallon planted freshwater tank. Fluorite substrate,
180gph power filter, 96watt Coralife lighting 6700 spectrum, temp
at 78. I live in a hard water area and try to do as little
"messing around" with my water as possible. Ammonia,
nitrites at zero. Nitrates at 15ppm (in local water
unfortunately). Ph 7.7, GH 22, KH 5. I add marine salt to raise
density to about 1.004.
<Sounds great. Thank you for these details.>
Tank residents are 3 Sailfin mollies (1male, 2 females), 4 female
swords, 2 Otos and 2 pygmy Corys (oh, and a random fry if the
swords aren't hungry).
All seem to be doing well.
My problem is with my plants. Most are doing fine. The anarchis
(sp?) grows so fast that I trim it at least weekly. The Ludwigia
looks spectacular and the Bacopa has doubled its original size.
The swords are doing fine though not growing quite as fast - same
for the Val.s.
<Swords need a deep substrate or they get root-bound. You can
try removing the swords, adding some more substrate in that area,
and then replanting if you want them to take off.>
But the Cabomba is horrible! It is dirty grey-green and shreds
apart if I touch it. I am seriously considering just removing it
as I would really love the real-estate to widen the Ludwigia
<Cabombas are touchy at best (I've never had luck with
them) They like very calm water and specific water chemistry. The
salt that you are adding for the Mollies is not likely helping
I also acquired (though I never intentionally ordered or placed)
some floating duckweed. It grows like gangbusters. I like it - it
is pretty and the fish seem to enjoy it. Just one problem - when
the floating plants hit the current of the filters they get
driven underwater. Most simply resurface a few inches away but
some get tangled in... well in just about everything!
<That sounds like duckweed.>
After a day or two I can easily have duckweed nearly covering
I even find it "trapped" under the edges of the
driftwood log. It is irritating and I worry, of course, about
shading out my other plants. Is there some trick that I don't
know to prevent this?
<Aside from manual removal, not really I'm afraid.>
I do not think I have too much current - there is very little
agitation on the surface. I currently "scoop" duckweed
out of the tank weekly and it seems to make only a small
difference. Anyone want a few handfuls of duckweed? :)
My second question is about the growing cadre of snails in my
tank. At first I diligently removed every one I could find. Then
a brief algae problem convinced me to give them a reprieve. Now,
algae is (praying hard here) under control and I don't think
I "need" the snails. Apart from appearances, is there
any good reason to remove them?
<Assuming they are not damaging your plant, I wouldn't
worry too much.>
Do they cause trouble?
<Some species can be destructive to plants, but based upon
your comments, I don't think you are having that
If I just leave them alone, exactly how many of these things will
I eventually have??
<Snails turn waste food into more snails. As the food supply
runs down (algae control) they will breed less frequently. Also,
most snails lay their eggs above the waterline, so you can remove
the eggs when you see
them. You can read here for more information:
Again, thank you so much for your site - I have spent many happy
hours reading and learning!
Tricia in PA
<MikeV in FL>
Re: Snails and Duckweed: FW Snail and Duckweed Control. Also
Plant health. 7/24/2009
Thank you for such a fast reply. If I may, a follow up or
I understand you to have said that there is no other control
mechanism for duckweed other than "scooping and
<It is the only method that is safe for your plants and
Do many aquarists keep duckweed?
<I know a few.>
Would you suggest that I declare war on the duckweed? Or just
keep blowing at it with my turkey baster and scooping out the
excess? Could I even win such a war if declared? :)
<That is a matter of personal preference. If you like how it
looks and are willing to live with it, by all means keep it. If
not, you can win the war by getting as much of it as you can out
every day for a week or so.>
As for the snails, I suspect that they arrived with some live
plants and that their population soared when the algae did. Now
that the tank is clean and clear... will they all die off at once
and foul my water?
<No, they are actually pretty effective when it comes to
resource partitioning, they will just slow their breeding
Will they begin munching on my plants (and with my luck, NOT the
Cabomba that I don't like ...)
<It is a possibility if they completely run out of food, but
that isn't likely to happen.>
Exactly how many snails are too many?
<Hehehe... when you think you have too many.>
Do I redeclare war? Selectively thin? Ignore completely? What is
<If you think you have too many snails, I would selectively
thin, This page: http://www.wetwebmedia.com/FWsubwebindex/fwsnails.htm
has an excellent method of "herding' them into one
place, making them easy to remove.>
Finally, I am having a hard time identifying the type of snail I
Actually, I know I have a couple of tiny ramshorns. These others
I am not so sure about. Could you look at these (terrible)
<Actually, those pictures are quite nice.>
Anything I need to know about them in particular?
<It looks like you have both Nerite and Trumpet snails. The
first 'in tank' picture is a trumpet snail. In your
second picture, the trumpet snail is the one on the bottom, and
the Nerite is on the top.>
<You can read more about them specifically. here:
And by the way, taking a close up of your tank is a great way to
convince yourself to clean a bit more frequently! Yikes!
<Hehehe, remember, a clean tank is not necessarily a sterile
Again, thanks SO much. My husband swears I spend as much time
reading your website as talking to him! (You DO know considerably
more about fish than he does... he likes his battered and fried
<Heheh, funny, my wife says the same thing about me.>
Thank you in advance.
<My pleasure as always.>
Tricia in PA
<MikeV in FL>
Snail Problem, comp., sel.
I have been reading feverishly for the past night and day regarding how
to safely remove snails from an aquarium. My problem is that all the
snails I have seen are located in my sump/refugium.
<Nothing really wrong with that, is there? Marine aquarists go out
of their way to put invertebrates in their refugia!>
75G FW with two Comet GF (6-8") and one Pleco (6-8"). Tank is
heated/chilled (it's a hobby...) to around 75/76F.
I have a 20G sump/refugium with plants (Anacharis, if I remember
correctly) that I purchased a few weeks ago, and this is likely where
they came from. I thought they were clean, but I was obviously wrong. I
have an Eheim 1262 pump in the refugium for return flow, and I need to
know if the snails/eggs can transfer through the pump into the main
tank? I have not noticed any snails in the main tank and boy did I look
around hard last night after finding the snails in the sump. The sump
has a 6" deep Seachem Fluorite
Black Sand substrate. Will the snails burrow into this?
<Some genera of snails are burrowers: Melanoides, Clea for example;
others, like Physa and Pomacea aren't really burrowers
I haven't noticed any, but then again, I might not be able to see
I've been reading that the
"put-food-in-something-and-remove-in-a-day" method helps
control population, and I will be doing this (cleaned salt shaker with
algae wafers in there now) over the weekend as I am leaving on a trip
tomorrow morning and won't be back until Monday night.
<Takes a long time to have much impact.>
However, I also know this won't kill/capture all of them, but
merely maintain the population. Since I have the plants in the
refugium, I'm concerned about them being eaten. I am also concerned
that due to the large
amount of algae in the sump/refugium, I'm never going to catch the
They don't seem to be concerned with the "free food" when
they have all they can eat off the glass. Which brings me to more
concerns, such as upsetting the balance I had with nitrates, and
potentially getting into the main tank where I will most likely lose
the war and have to restart the entire aquarium (something I'm not
really wanting to do for obvious reasons and since I don't want to
put the fish through the stress).
<Repeat after me: Snails are harmless. There is X amount of protein
in your aquarium, and some goes into the fish, the rest into the snails
and heterotrophic bacteria. The snail population expands to equal the
amount of protein. Provided you don't overfeed the tank, the snail
population CANNOT expand indefinitely. It reaches a level. In itself,
all the snail population does is speed up the decay of organic matter
into the ammonia that the nitrifying bacteria can use.>
I've also read that chemicals, like Had-A-Snail is a bad idea for
the fish and possibly the plants.
It especially says to "take care with catfish". Not something
I'm willing to risk unless the experts (you) say it will be ok for
<Snail-killing potions do more harm than snails do! Think about what
happens if you kill all the snails, and they rot away all at the same
Ammonia spikes galore!>
But, I've also read that Fluke tabs may solve the problem.
<Copper at least will kill all sorts of invertebrates, but it's
also toxic to fish, some more than others. Catfish, loaches, Mormyrids,
puffers are among the species most intolerant of copper.>
However, I can't tell from reading online and the manufacturer
instructions how detrimental it will be to catfish and plants. This
would obviously be the easy solution and I'd be happy to try it if
you guys think it won't hurt any of my fish. I would take the fish
out of the aquarium if I had another place to put them, but
all I have is a 10G tank I use if I ever have to move/do construction
on the main tank. This is definitely not a suitable home for them for
more than a day.
<Specific fluke medications other than copper will have little/no
impact on snails.>
Another idea I read about, a loach, doesn't seem feasible as the
environment just isn't suited for them. I'd hate to put a fish
in a place that isn't suited for them just to help me out. No
reason it has to suffer for my mistake.
I was thinking the following in regards to killing the pests: Replace
the sump for a couple of days with a canister filter I have and remove
the water from the sump leaving it mostly exposed to air (the sand
holds a good amount of water) and attempt to "dry out" the
snails. Does this work? Will the snails die out of water?
<Some will, but others, such as Melanoides, can survive for months
out of water in a hibernating state.>
Will they try to burrow into the sand?
<Some will, yes.>
If that isn't a good idea, what about mixing only the water in the
sump with a large dose of aquarium salt? If I do this, will the sand
absorb the salt?
<Melanoides can tolerate up to 50% seawater, so your plants and fish
will die long before they will...>
Will the plants die if I leave them in there? I want to try to
disinfect everything I can, so I'd attempt to leave pumps and
heaters in the salt water if I did this.
Will this be fatal to the fish upon reinstalling the sump? I understand
I can dilute, like a couple of 100% water changes, but I'm worried
it will ruin the substrate which will kill the plants and harm my fish.
find any of this information on your site. Surely I can't be the
only one that ever had a sump infected with snails, but then again,
maybe I'm one of the rare people running a sump on a FW tank?
<Snails aren't that big of a problem. Simply remove the surplus
snails as you see them, but otherwise ignore, and instead control
excess protein via better aquarium management.>
Help! And THANK YOU so much!
<Do see here for a useful snail-eating snail, Clea helena.
Widely sold in the UK at least, sometimes as the "assassin
Snails, FW, sel., contr. 09/08/07 Hi crew, The
other day, Neale gave me some advice on keeping my sand 'safe'
for my freshwater tank. It was suggested that Malayan livebearing
snails would be good to keep the sand aerated and to eat debris, etc.
It's just a small 6gal., and so far just two fish. So I've done
some reading, but here's my questions. If I get the Malayan snails,
seems they'll reproduce prolifically; will they eat up all the
algae? I'm worried that my Otocinclus won't have enough to eat
if this happened. Also, being that they would reproduce so much, do
they contribute to the bio or waste load much; or is it negligible?
Thought I'd ask since my tank's so small. Lastly, would the
water condition needs differ much from the Oto? Thanks so much! Vanessa
<Hello Vanessa, Malayan livebearing snails (Melanoides spp.) do have
a bad reputation among some aquarists, while others consider them a
blessing. I fall into the latter camp. Here's why. Melanoides turn
organic material into snails. They don't eat gravel, they don't
eat sand, and they don't eat live plants or fish, EVER. So if the
Melanoides are multiplying, they only do so because there's
"stuff" in the tank for them to eat. That might be uneaten
food, it might be decaying plant leaves, it might be a dead fish, or it
might be algae. Provided you keep the tank free of those things, the
snails won't multiply very much because they can't. In a clean
tank where all they have to eat is algae and tiny amounts of organic
detritus, they just don't become a problem. They may be breeding,
yes, but they're dying too, so you end up with a more or less
steady population. It's in messy tanks where people have inadequate
filtration and overfeed their fish and don't remove dead plant
leaves that the snails become problematic. Even in large numbers
though, they don't do any harm, and removing them isn't
especially difficult. You can buy little snail traps for about $5-10
(it's called the JBL "Limcollect") and you could use one
of these every six months or so if you thought things were getting out
of hand. Some folks make their own lobster pot-type traps from small
plastic cartons and the like. Since the snails crawl onto the glass at
night, it isn't difficult just to turn the lights off early one
night, and then wait for the snails to emerge, and then scrape them off
with a net or suck them up with your siphon. It's no big deal. But
really, I leave them to their own devices. No, they won't
out-compete you algae-eating catfish, and no, they don't add much
to bioload on the filter. On the plus side, they ensure there's no
anaerobic decay in the tank and they help aerate (if that's the
word) the substrate encouraging good plant growth in the same way
earthworms do on land. They are also very good "early
warning" monitors: if you see them on the glass in the daytime
making a bee-line for the surface of the tank, it means you have a
problem. As far as water chemistry goes, they're not fussy. In
soft/acid water they tend to reproduce very slowly, which may or may
not be a good thing depending on your needs. I'll also add that
they are extremely pretty little animals. Take a look at one close-up:
they have beautifully sculpted shells with red and purple markings. If
they were rare and difficult to keep, aquarists would covet them... but
because they're so easy to keep, we scorn them. Strange. I hope
this helps, Neale.>
Persistent High Nitrite Level FW 1/31/06 I have read
other messages on your site and other articles on other sites about
high nitrite levels, but I still don't quite get it. I have a 10
gallon tank with 10 fish: 2 balloon belly mollies 2 ghost catfish 5
orange von Rio tetras 1 algae eater There are many, many small snails
that were acquired accidentally with an aquatic plant that died some
time ago. . . The snails, however, live on and reproduce at a
staggering rate. <Mmm, you might want to collect and remove a bunch
of these periodically... easy to draw to a small glass tray with a
sinking bit of algae based food or blanched vegetable... as bait>
Until today, I had a philodendron sticking out the top of the tank with
its roots submerged. I took it out thinking that this was perhaps
contributing to the problem. <Oh! Yes> About a week ago one of my
mollies (there were three) started to act strangely as if she
couldn't submerge. She would still eat when given food, but
couldn't swim down to eat off the bottom like she always had. She
had also lost a lot of weight. Eventually, she became very lethargic
and got to the point where she was upside down and couldn't turn
over. I took her and another sample of tank water to the local pet
store. They said it didn't look like she had any disease and
offered no explanation as to her condition. I assumed it was just old
age and I only include this description in case it is symptomatic of
some other problem. Anyway, when the girl at the store tested the water
(something I had never done--shame on me), she said that the pH level
was low and that I should increase it with a pH increaser. I bought the
pH increaser and a test kit that tests for NO3, NO2, GH, KH, and pH.
When I got home, I did a 30% water change and added 1 tsp of salt,
which is my normal routine. (I keep around 3 tsp of salt in the water
at all times.) I did not add any pH increaser. I tested the water
immediately afterward and it looked OK except the water was hard, so I
added a teaspoon of salt. The next day, however, the levels were as
follows: NO3 = 40 <I'd keep this under 20 ppm> NO2 = 1.0
<Dangerous... should be zip, nada, zilch> GH = 300 KH = 0 pH =
6.8 I added another teaspoon of salt and changed the filter which was
very dirty (because I had made the water very silty the last time I
changed it--explanation below). The next day, the nitrite level was at
3.0. <Yeeikes!> I did another 30% change and waited an hour
before testing. The nitrite had gone down to 1.0. One day later, it was
back up to 3.0. The next day, 3.0 again. The following day, 5.0. Today,
it was still 5.0 so I did another 30% water change. One hour later, the
levels are as follows: NO3 = 40 NO2 = 3.0 GH = 150 KH = 40 pH = 7.2
There is currently about 8 teaspoons of salt in the water. <Mmm, you
might want to mix some of this salt up in tapwater and test it for
nitrite...> The strange thing (to me) is that the fish seem to be
happy and healthy. From everything I have read in the past few days, a
5.0 nitrite level should have them dropping like flies! <Let's
see... luckily your pH is low... if it were a little higher, the
nitrite would be MUCH more toxic> I have checked for brown coloring
of the gills and see none. They are not gasping for air at the top of
the tank either. I can only surmise from what I have read that the salt
is keeping the nitrite from being as toxic as it otherwise could be.
<Oh, yes... this also> I have noticed the mollies scraping
themselves occasionally on a structure in the tank. I read today that
this was one sign of nitrite poisoning. I have had this tank for 8
months now and only three fish have died in that time (except for the
batch I introduced right at the beginning before the tank had cycled!).
About a month ago, I did a very thorough cleaning of the tank. I really
stirred up the waste on the bottom, trying to get as much out as
possible. I took out all the structures and washed them with hot (not
soapy) water. I changed the filter as well. I also started feeding them
much more around that time. Basically, I unwittingly did everything I
could to raise the nitrite level! My questions are this: 1. Why
isn't the level decreasing? <I suspect the houseplant> 2. Why
are the fish still alive and acting normal? <They're tough,
adapted to it, and the salt> 3. I have read on some sites of a
biological filter or a biofilter: Is this (a) just another name for the
normal filter, <Mmm, of a sort... all filters are ultimately
biological to degrees> (b) a different kind of filter that I should
have, or (c) just a term that refers to the nitrogen cycle that occurs
within the tank? <Mostly the latter> 4. Could the snails be
causing problems? <Yes... carry disease... and can influence water
quality in high numbers> 5. I have read that most of the bacteria
live on the filter. Wouldn't changing the filter then lead to these
levels getting all out of whack every time? <Yes... a common
problem/occurrence. In established systems not such an issue> Thank
you for any help you can provide. - Bryan <I would read over WWM re
FW filtration, add more filtration, remove the houseplant, reduce the
number of snails, test the salt... Bob Fenner> Re: Persistent
High Nitrite Level... Betta systems and snail removal technique
2/3/06 Thank you. After removing the philodendron, the nitrite
levels immediately dropped and are now < 0.5 ppm. Other levels are
beginning to even out as well. <Ah, good> I thought you also
might like to know that I have rigged up a plastic fork on some fishing
line as a snail remover. I stick a piece of vegetable on the tines of
the fork, and when a few snails crawl on, I hoist it up and scrape them
off. It's not pretty, but it's been fairly effective! <Neat!