FAQs on the Molly Health/Disease: Diagnosis
Related Articles: Mollies, &
Poeciliids: Guppies, Platies,
Swordtails, Mollies by Neale Monks,
Livebearing Fishes by Bob
FAQs on Molly Disease:
Molly Disease 1,
Molly Disease 2,
Molly Disease 3,
Molly Disease 4,
Molly Disease 5,
Molly Health 6,
Molly Health 7,
Molly Health 8, Molly Health ,
FAQs on Molly Disease by Category:
Nutritional (e.g. HLLE),
Social, Infectious (Virus, Bacterial, Fungal),
Parasitic (Ich, Velvet...),
FAQs on Molly Reproduction/Breeding:
1, Molly Reproduction 2,
Molly Reproduction 3,
Mollies. Again. 2/14/17
Hi, Neale - long time, no questions! Hope you had a good holiday and that the
new year is treating you well.
<All good; thanks for asking.>
This morning we noticed that we have a silver sailfin Molly that's just lying on
the bottom or swimming lethargically, using only her pectoral fins. She doesn't
use her tail to swim at all. Her tailfin seems kind of shredded lengthwise, but
doesn't look bitten. She had gotten big, we thought she was pregnant (assuming
one of the 7 young mollies is a male),
but she seems slimmer now. We have seen any fry in the tank, though we didn't
really look (I'm only just now thinking of it).
We have another Molly, a creamsicle, that is starting to shimmy.
<Typically a stress reaction, though quite what the stress factor might be isn't
always obvious. Mollies are easily stressed by chilling, nitrate, and the wrong
water chemistry, though like all fish, non-zero ammonia and nitrite are issues
The numbers are good in the tank - ammonia and nitrite are 0, nitrate is 20.
<Sounds good, but no mention of water chemistry here. Will (re-) state the
importance of carbonate hardness to Mollies; alkaline water with a basic pH is
an essential, especially if salt is not added to the water. Tanks will acidify
between water changes, and this causes problems for Mollies in particular.
Simply doing a substantial water change or three will often help Mollies return
to their normal happy selves. Failing that, adjusting water chemistry slightly,
by the addition of sodium bicarbonate -- one teaspoon per 40 litres/10 US
gallons is a good start. Easiest approach here
is estimate size of tank, make up the correct solution for that volume, and then
add to the tank in small amounts across a few days, giving time for the fish to
adapt. Alternatively, just add the right amount of a given bucket of water (so
might easily be a quarter teaspoon for a 2.5 gallon bucket) and do your water
changes as per normal. I do prefer to keep
Mollies in low-end brackish conditions, but understand that isn't an option in
all cases. Read up on the pros/cons of this, and act accordingly. Would also
check the heater, and maybe turn it up a notch, Mollies preferring quite balmy
conditions compared with standard community tank fare; 28C/82F is not out of
line for the bigger, sailfin varieties in particular.>
Tell me what I forgot to tell you and I'll provide the info, but this is about
it, that I can see. As always, thanks so much for your help!
Tom & Maria
re: Mollies. Again. 2/14/17
The water is relatively hard, and it goes in at around pH 7.8, then the tank
adjusts up to 8.0 to 8.2 with the bubble stone and stays there. Maria changes the
water weekly at a 25% change. The numbers have all been stable NH3/4, nitrate,
nitrite, pH, etc, for months.
She's still hanging in there, but in a head up position. Could this be
<Yes, but environment is what you look at first. If you're content that the tank
is good, then sure, treat with an antibiotic. Livebearers are sometimes given to
strange "wasting" diseases after a certain length of time -- whether old age,
dietary shortcomings (do bear in mind they're herbivores in the wild), social
stress, or inbreeding is hard to say. But
colonies of livebearers frequently do well for years, but individual fish may
have substantially shorter lifespans than you might expect.>
Why would the tail separate into lengthwise strips?
<Typically physical damage, such as fighting. Do bear in mind Mollies are prone
to fighting. You could medicate as per Finrot, but keep a close eye on the fish
for evidence of squabbling. Cheers, Neale.>
Re: Hello and Thank You 1/24/17
Happy New Year.
one of my mollies has swollen, red gills on one side. the other
side looks ok. I change water weekly: ammonium, nitrite are 0. nitrate has never
been above 40ppm. what could cause this problem?
<Difficult to say. If just the one side, physical damage is certainly possible.
Fighting, failed predatory attack; getting stuck on a filter inlet; clumsy
handling by a human with a net can all damage the opercula and the gills
underneath them. If the fish is otherwise healthy (in particular: a healthy
weight, nice and active, and not showing signs of things like greyish mucous
patches on the flanks) I'd tend to leave things be. But if alongside other
maladies, might be worth using an antibiotic. Mollies can exhibit "wasting"
symptoms that typically include fin clamping; rocking from side to side ("the
Shimmies"); concave flanks as they lose weight; mucous/pale patches on their
flanks; and a general appearance of
lethargy and disinterest.>
Sick Molly's; no data, rdg. 10/7/15
I am not sure if I am in the right area but I need some help my water is 0.05
<.... is this specific gravity? If so; likely you mean 1.005. What salt/s did
you use here?>
I have mollies with some weird symptoms started out like dry looking patches and
now looks like this orange one she is the only one that looks like this they
start out like the balloon Molly and progresses there are only 3 I can see that
look like this but only the orange that looks this bad I found 2 baby's with
what looks like little holes in there head and one baby his eye was white and
pooped out I believe
<... need more data; re water quality, system, maintenance, feeding, history of
the system. Let's have you read here:
and the linked files above.... for input, and to grant you an idea of what sorts
of info. we're looking for. Bob Fenner>
Re: Sick Molly's 10/7/15
Sorry I am sick and not functioning on all cylinders myself it is specific
gravity and it is 1.005
<Mmm; if you had other livestock.... than shown in your pix; I might well be
raising the "saltiness" here>
I use marine salt by instant ocean
tank is over a year old and cycled I use SeaChem stability and ammonia alert
it's o it only measures free ammonia but I also checked with a ammonia tube
tester it shows zero I use a biological cascade 1000. I do 15% water changes
weekly. I test with high range ph test kit it is 7.5
Nitrite is 0 nitrate is 5.0
I have had issues with phosphates getting up between 1.0 and 2.0
<Meh; not to worry>
but use a phosphate remover, also by SeaChem. I only have 1 live moss ball
in the tank it has really good oxygenation I have 1 Plato
<Pupil of Aristotle?>
1 shrimp a few zerite snails
it's a 45 gallon corner tank and 4 adult female mollies, 6 juveniles and
honestly could not tell you how many babies my levels were fine so didn't
worry about it I want to give them away but can't till I know what's up in
this tank I got Molly's all at once never added any more snails were added
after and shrimp feed omega one twice daily micro pellets for babies or
crush the omega one in a pill crusher I do both I have city water, use aqua
safe to remove chlorine my temp is 80.2. I have used Metronidazole in the
water it was by apI twice
<Don't keep putting this in: Toxic>
48 hour intervals then I started giving mixed 1/8 tsp api to 1/2 tbs omega
one soaked in 1/2 tbs water for 30 min now I have started using life guard
<For what? What for?>
while waiting to find out if anything can be done.
<...> really <...>
I have not seen anything like the pics I have sent you, do you have any idea
what this could be I believe my mollies came with whirling disease I had the
whirled for a year I euthanized her when she finally stopped eating I kept
her in a floating baby nursery with a nylon bottom lost a lot of babies to
this disease it finally stopped I hope.
<.... wish I had a microscope nearby there.... Do you have another system
you can move just the mollies to; jack up the salinity? BobF>
Re: Sick Molly's 10/8/15
I have them in a separate quarantine tank just has the 2 mollies a baby Molly
that is twirling but has since stopped a baby with a white eye and 2 small
babies with what looks like a tiny whole in there head nothing else in this 15
gallon quarantine tank
<Do see my previous message, and Bob's; do also read:
Mollies aren't difficult to keep in (very) hard or (even slightly) brackish
water, but are endlessly delicate if kept otherwise. Sensitive to crowding,
nitrate, cold, and various other factors. Cheers, Neale.>
Re: Sick Molly's 10/9/15
Well I thought I read everything but got nothing I didn't already know
my levels are fine in everything,
<Please don't tell me this. It's no use to me. What, specifically, did you
measure? What numbers did you get? Many hobbyists think their tank is
"fine" but they're not. By "everything" do you include salinity? pH? Hardness?
but I didn't read anything that you thought it might be or what to try I am old
and have worked really hard to help them they came sick with clamped fins in
fresh water of course, I have read a lot on that site you sent a long time ago,
if you sent something that might help I must have missed, I think I am done,
euthanize the lot 9 separate tanks because of all these
babies, but they all come initially from the same tank,
<Seems a bit extreme. Let's review. Mollies are most sensitive to environmental
issues. Specifically, coldness (keep them at 25-28 C if possible); acidity (keep
them at pH 7-8.5); and hardness, most easily dealt with by keeping them in
brackish water, around a teaspoon of salt per litre (about 3-4 per US gallon)
being about right. Farmed Mollies can suffer from
some "catchy" diseases, with Camallanus worms and "Slime Disease" (also known as
Costia) being the two most difficult ones to medicate against. By contrast,
while Fungus and Whitespot do occur, as does Velvet, all these are easily
treated. But do remember to remove carbon from the filter before using
medicines. Finally, using salt often helps moderate or even eliminate diseases.>
I feel I can't find new homes till I know what's going on. So it's time to
euthanize unless I can come up with something else to try. Maybe I missed
something I will go back and look but I just saw the one message and it was hard
<Hmm... not sure this is difficult to read, and would start here:
Most fish health problems are environmental, especially where many fish are sick
at the same time. Review conditions, or at least TELL ME the values on your test
kit, and we can take it from there. Cheers, Neale.>
Re: Sick Molly's 10/10/15
I told you all the values when I started messaging you about the mollies I use
specific gravity to test their saline,1.005 I have sent numerous messages in the
past few days with pictures and gave you all the values in the tank, how I feed
what I feed and there not all sick and only this fish looks like this and I felt
was getting any info on meds or how to help so euthanized today
<May have sent this information before Colleen, but there are several of us who
help out at WWM, and I don't recall reading a message with those values. Try to
imagine what it's like for us. We get hundreds of messages a week, and simply
can't keep track of every bit of information. So when someone says they sent a
message to us last week with a piece of
information in it, that's a lot less helpful to us than resending that piece of
information in a new email. Just the way it works, Colleen, I'm afraid. We're
volunteers, we're offering a free service, and what we're trying to do is
incredibly difficult. Imagine a doctor diagnosing a human illness by email.
That's the situation here. If your fish tank was in front of us, and we could do
all the test kits immediately, that'd be great. But we aren't with you, and we
rely on you to do the tests. If you can't send test kit information to us,
you're basically asking us to figure something out with 90% of the important
information missing. I'm not exaggerating there. Water quality and water
chemistry are the two main reasons fish sicken and die. All the other reasons
These are some better close ups I am old and not feeling well so I just can't go
through all the info again I am sure if you go back and read you will find what
<Indeed you had, and with a bit of effort I've found them. pH 7.5; fine.
But no information on hardness. Let's assume it's adequate. Specific gravity
1.005 is excellent. Nitrite you say is zero, nitrate 5.0. This latter value is
very low, which is good, but I'm normally skeptical of such low nitrate values.
Why? Because most urban and suburban water supplies are well over 20 mg/l
nitrate, often 40 mg/l. Certainly in England where I am!
But if you're out in the countryside somewhere and use well water or something
with very low nitrate, then your test reading might be accurate.
Nonetheless, keep an open mind about this nitrate value. Test kits don't always
measure accurately, or may be difficult to read.>
and to be honest you guys are who ever I have been messaging with have been
snappy, the rolling eye comment because I told you I was using life guard,"
because I did not know what else to do while I was waiting for
information"!!!!!! And you asked why I was treating with life guard, then did
that eye comment thing.
<Hmm... I don't think these comments came from me. But in any case, we're
sometimes snappy because we've got a lot of sick fish questions to get through,
and it can be frustrating sometimes when we're dealing with willful ignorance --
not in your case, but does happen rather often, where people hang on to ideas
(like Bettas can live in unheated bowls) because they
prefer ignorance (and fish dying, only to be replaced a week later) from
accepting they're wrong (and spending more money). As folks who like pet fish
and turtles, what we mostly help with here, we get a bit worn down by this at
times, and it may become obvious if we're a little short at times.
Don't take it personally. If we were really mean people, we'd not be doing this
for free, and we'd have just ignored you. Judge a man by his actions rather than
his words, is what I'm saying.>
After I told you why I was using it. I am not a expert but do care about my
fish, have worked very hard to help them I have purchased more and more tanks
because of the crowding, I am just euthanizing any sick fish I see, I have tried
for a year to get a straight answer and can't so I am done,
<Sometimes there just isn't a single straight answer. Mollies are plagued with
problems in the US especially, kind of how Neons and Guppies are here in the UK.
I guess breeding a fish to a price point rather than a quality has been the
cause. But in any case, some problems are difficult to diagnose. Your fish may
well have had more than one problem, and while I
suspect the blisters (which I hadn't seen clearly before) are from exposure to
some sort of toxin, it's hard to say what. Blisters aren't normally caused by
common disease organisms, or genetics, but tend to be environmental, sometimes
mediated through a viral infection (such as Lymphocystis, which is untreatable
but not normally fatal, and often clears
up after some months, even years). Even if you think the water is 100% perfect,
it almost certainly wasn't. Copper perhaps, or something airborne like paint
fumes might have been getting into the water. It's really hard to say. On the up
side, since this isn't likely to be contagious or genetic, any healthy Mollies
should remain healthy if their environment is good. Review, as previously
discussed, and act accordingly. Think about what might have been getting into
the water, and perhaps swap your current water conditioner for something that
specifically neutralises copper, ammonia and heavy metals. Relocate the tank if
it's somewhere near a source of fumes, and perhaps use carbon in the filter (not
normally a fan) and see if that helps (will need replacing every couple of weeks
though). Carbon has the useful trait of removing certain dissolved chemicals
from the water that normal filtration does not.>
maybe you just did not get my e-mails and all the info and pics I sent you,
thank you for your time have a nice Day.
<There's no single answer here, which I'm sure is frustrating. But much to think
about. Cheers, Neale.>
Mollies dying; diag., trtmt.s f' 9/1/15
I apologize I hit send before checking my grammar and spelling, as I am
messaging from my phone...I will correct...
<Not a problem.>
Dear WWM Crew,
I noticed you had another person named Jace email you back in March of 2011 with
similar issue that has not been solved and was wondering if you have any more
insight now that some time has passed... I had 2 white mollies, 2 black mollies,
1 orange balloon sailfin molly and 1 gold panda molly in a 20 gallon cycled tank
(fish purchased approx. 1 month ago), frequent water changes done (25-40% per
wk),with regular testing, 0 ammonia, 0 nitrites and 5 nitrates (no spikes during
this recent time) the mollies came from brackish water so I have kept this
environment for them.
<Can you tell me how much salt you're adding? Brackish water suitable for
Mollies would be something like 5 gram/litre (0.65 oz/US gallon). That gets you
a specific gravity of 1.002 at 25 C/77 F. You can use digital scales at home to
work out how much you'd want to add per bucket. For a 3 gallon bucket for
example, that'd be 3 x 0.65 = 1.95, close enough to 2, oz per bucket. Make
sense? Once you've measured it out you can use teaspoons and see how many
teaspoons there are in that quantity of salt. It's about 5 teaspoons per 1 oz of
salt, more or less, so we're talking about 2 x 5 =10 teaspoons per 3 gallon
bucket. With me so far? Mollies will actually do even better at higher
salinities, and even doubling this amount of salt
could be worthwhile if your aquarium is just Mollies and plastic
plants/ornaments (real plants and most other fish won't be so keen).>
Anyhow, first I noticed definite Ich symptoms - as the black mollies, orange
molly and panda molly were COVERED in white dots like salt grains (couldn't
quite see any on the white mollies). I raised the temp to 86 degrees to speed up
life cycle and increased the salt in the water to 3tsp per gallon
<3 x 6 gram per US gallon... 18 gram/US gallon... 18 gram/3.8 litres... 4.7
gram/litre... yes, that should certainly kill of Whitespot and Velvet.>
when white spots disappeared to kill the ich the natural way (without meds)...
<Salt is a medication... in some situations far more harmful than, say,
Now, before the white spots disappeared, 1 white molly's tail fin just
disappeared (frayed down the body) and then back half of her body started to
look fuzzy and she just kept spiraling around tank so I euthanized her.
The next day, the 2nd white molly's mouth was swollen open & just started
crashing in to the gravel upside down, gills heaving and could not move so I
euthanized her also.
A few days later, the orange balloon molly's lips looked the same, she crashed
and died just like the white molly! So, I assumed the Ich overtook the fish
because this all occurred before the white spots fell off any of the fish and
the other fish were COVERED in salt grains so it just made sense.
<Possibly, but I'd be wondering if Velvet or even Costia is the issue here.
Costia is the old name for Ichthyobodo, and you'll see both names in aquarium
books, though Costia (or "Slime Disease") are more often seen on medications. In
any event, like Whitespot we're talking about a microscopic protozoan that
latches onto the skin of the fish and causes damage. Costia does seem to become
more lethal more quickly than Whitespot or Velvet.
Commonest symptom is the appearance of off-white patches (rather than the
discrete salt grains of Whitespot or icing sugar/golden sheen of Velvet).
It's more difficult to treat than Whitespot, though some medications will treat
both. Brackish water works well against it though, as do 2-20 minute seawater
dips (35 gram/litre). Mollies tolerate seawater dips extremely well, so this is
a useful approach. I'm mentioning Costia here because it's a bit of plague among
Mollies, notoriously obvious on Black Mollies because of their colour, often as
greyish patches on the face and flanks.>
So after a couple days of raising the heat slowly, the white spots all
disappeared and I started the salt treatment (to kill the free floating Ich),
when all of the sudden (now this is when it gets exactly the same as the email
you received in 2011 that I found on your site from Jace that had no resolution
or real answer) the 2 black mollies started hanging around the filter intake and
the heater near the surface (but not gasping), with their tails down as if their
tails were paralyzed (drooping) and if they swam under the waterfall from the
<This is the famous "Shimmies" when Mollies are stressed and unable to swim
properly. It's called the Shimmies because initially the Mollies rock from side
to side as they tread water, as if shimmying.>
they were forced into somersaults uncontrollably but then would buoy back up to
the surface, tail down again. I also noticed their bowel movements were a long,
clearish-white hair-like string (with intermittent white beads every so often).
<Interesting. Copious white faeces indicate excess mucous in the gut, which in
turn often points towards parasitic infections, most notoriously, Hexamita.>
The next day, one black molly started crashing nose down into the gravel and
could not swim or right itself (just as the white ones!) He stopped breathing
and I noticed its anus was extremely white. Now the other black molly is still
hanging near the surface with her tail down, obviously about to suffer the same
fate! The only other one left is the gold panda molly and she seems fine! Again
no parameters changed drastically ever during this time, and the only
identifiable problem I saw was the Ich, but, as I said, it cleared up before
these last 2 started crashing and they started displaying these unidentifiable
symptoms that even your site said were strange (back in 2011)...so, I'm
wondering if anyone has any ideas?
Any new knowledge on this? Could it be Ich AND something else?
<Easily. Whitespot/Ick is pretty much ubiquitous, but it's so easy to treat in
its early stages it shouldn't ever be lethal. But it's also easy for fish to
pick up other infections, and among livebearing fish, Camallanus worms, Hexamita
infections, and something called Tetrahymena are all worth thinking about.
Hexamita is treated by using Metronidazole, and is discussed elsewhere on WWM;
use the Google search facility on the top of each page and you shouldn't have
any trouble finding out about Metronidazole (often used alongside an
antibiotic). Now, Tetrahymena is something less widely discussed. It is
sometimes known as Guppy Disease.
Superficially similar to Whitespot in terms of symptoms but far more immediately
lethal. To save me rewriting a bunch of stuff about this disease, let me direct
you to a piece about this disease I wrote over at FishChannel:
The bottom line is that there are no effective cures, though a combination of
anti-protozoan medication (Metronidazole for example) alongside elevated
salinity (the higher, the better) may help.>
I forgot to mention all the fish were purchased together and introduced to the
cycled tank at the same time (which I would never do again obviously!)
But I am very curious what this is and what to do now? I don't want to proceed
ignorantly and subject any more fish to whatever this issue was!
Please help as I cannot bear to lose any more or have to euthanize; I am an avid
animal lover and it's breaking my heart!!
<Hope this helps. Cheers, Neale.>
Re: Mollies dying 9/2/15
Thank you so much, I will look into all of this information!
<Glad to help and good luck. Neale.>
Hi I am worry about my black Molly it has a white spot on its neck just before
its fin i don't know if I should go and buy a small tank and put it in because
the tank has the new babies in it by the way my tank is 65gal and the other one
is 20gal thank you
<Mmm; just one spot.... I would not over-react; would NOT treat or move the
fish. The water in this system is hard and alkaline I take it; these fish fed a
good deal of green-based foods? Bob Fenner>
balloon molly with growth
I have a Dalmatian balloon molly with a growth behind its right fin.
<Ahh; see this in your pix...>
looks like a solid mass, grayish green in color, consistently growing. I would
say it has doubled in the past few weeks. Please see attached picture. I would
appreciate any insight.
<Such growths are more and more common... tumorous; from various supposed
causes... Narrowed genetic bottlenecking from so-much inbreeding,
hybridising... perhaps water quality, nutritional input. Naught to do re
treatments other than improving the environment and foods/feeding. Bob
Re: balloon molly with growth
So basically she is going to die....and there isn't much I can do to help?
<Mmm; perhaps not die soon; but nothing that I'm aware of... other than
experimental surgery, medicine use>
If I am understanding your last sentence correctly, you are saying there isn't
much that can be done in regard to treatments for the condition.
However, I can monitor water quality and nutritional input....? Are there better
fish foods than others?
<Yes; please see WWM re Molly feeding. BobF>
Poecilia velifera Parasite or Bac. Concern
Greetings Crew, I've recently purchased(2 weeks ago) a few Sailfin
I have them in 40g breeder quarantine tank filtered by a small aquaponic
grow bed(7 gal), homemade interior filter and air stone. One female has
a large stomach with no gravid spotting and does have a very slight
prolapse in rectum.
<Mmm; perhaps a bit of Epsom Salt>
This fish is mostly clear(in coloration) and I've noticed a black, some
what blotchy pigment spreading under skin. It started behind gill plate,
down toward stomach and slowly progressing backward. The fish seems
healthy aside from conditions mentioned, feeding well, active, etc. No
other fish are showing symptoms.
<What other fish/es (species) are present? The water is hard,
alkaline... salt/s present?>
The other females have delivered fry except for this one. I'm
considering treating for parasites and/or bacterial infect.
<Mmm; dangerous to just add medicines w/o knowing specifically what
I have Metronidazole
<Toxic... just one dose. See WWM re>
on hand and was considering using it. I also have Furan and PraziPro. I
do have access to Oxytetracycline, if need be. Which would you
suggest, if any at all?
<Again; none w/o better knowledge of cause/etiology here>
My water supply is "hard"
and I do add marine salt.
<Ah; good... IF your other life can/will tolerate it>
Do you think I could omit the salt without any negative consequences?
<Can't say w/o knowing more... the other life present mostly>
Thanks for the great site. Aloha Brandon
<Welcome. Bob Fenner>
Re: Poecilia velifera Parasite or Bac. Concern
Thanks for reply Bob. These fish are quarantining in a tank just
containing 4 female and 2 males sailfin Mollies.
<Ahh, thank goodness>
Really haven't noticed aggression towards any fish. The fish in question
seems to be the most dominant fish in tank. Soon to be added to a larger
school of strictly Sailfins. My water hardness hovers around 75mg/liter,
ph of 8.3.
<Ahh; about what ours is>
What would be the best way to ID an internal protozoan infestation on a
<Sampling... and microscopic examination. A bit of this is gone over...
Thanks for the help. Have a great weekend. Aloha Brandon
<And you, BobF>