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FAQs on Freshwater Infectious (bacterial, fungal) Diseases: Causes, Etiologies, Prevention

Related Articles: Freshwater Fish Diseases, Freshwater DiseasesFW Disease Troubleshooting, Choose Your Weapon: Freshwater Fish Disease Treatment Options by Neale Monks, Understanding Bacterial Disease in Aquarium Fish; With a gallery of bacterial infections, a discussion of 'Fish TB', and a listing of major antimicrobial medications with examples available to fishkeepers By Myron Roth, Ph.D.,

Related FAQs: Infectious (bacterial, fungal, viral) Disease 1, Infectious FW Diseases 2, Infectious FW Disease 3, Infectious FW Disease 4, Infectious FW Disease 5, & Infectious Disease: Identification/Diagnosis, Cures/Medications, Case Histories: Bacterial, True Fungal, & By Type/Organisms: Fin & Mouth Rot, Columnaris, Mycobacteria/Tuberculosis, Whirling Disease, Bettas w/ Infections,

... too much stress...
Poor water quality, a lack of nutrition...
Unsuitable species, too small an environment

Gymnarchus niloticus with white eyes - 6/12/10
Dear Crew,
Amazing website - the wealth of information has certainly helped so many of us to care for our fish better.
<Nice of you to say so.>
I purchased a young 14 cm Gymnarchus niloticus two months ago,
<Still a baby.>
and it has been housed in a 180 litre tank with plenty of cover and filtration. I know it grows to an enormous size and I'm making preparations for a much larger tank for it.
<These fish are gigantic and notoriously aggressive. They are not really suitable for home aquaria.>
However, it's eyes have recently turned white. Nitrites and Nitrates are at a low but not completely zero, which I fear may have been the cause of the disease.
<Correct. Chronically poor water quality will cause skin infections, including damage to the cornea, which is the issue here. But I suspect physical damage is the aggravating factor, e.g., by throwing itself into the glass walls of the tank. Also be aware that live feeder fish can introduce a variety of parasites and infections, including Eye Fluke, so
should never, ever be used. Other possible causes include exposure to chlorine (i.e., incorrect/no use of water conditioner) and poor diet (specifically, vitamin A deficiency).>
I first thought it was a cotton wool-like fungus that grew over its eyes, and I have added some medication for external fungal and bacteria.
<Unlikely to help without establishing the causes.>
But after a week of treatment, it has not shown signs of getting better.
After closer examination, it seems that the lens itself are white, and thus I now suspect that it could be Cloudy Eye Disease. I want to hear your opinion on it from the photos attached before I treat with different medication.
<You really do need an antibiotic -- not an antibacterial -- and you also need to optimise water quality. Zero ammonia, zero nitrite.>
If it is cloudy eye, I understand that I will have to use antibacterial medications. As Gymnarchus are similar to Mormyrids, do you think I will need to lower the amount of medication added?
<Avoid malachite green, formalin and copper. Antibiotics and methylene blue should be fine.>
The fish is still eating and moving around well.
<And will likely lose its eyes, unfortunately.>
Thank you for your comments,
<Cheers, Neale.>

Fungus won't go away and is spreading. (RMF, do you think tea-tree oil is to blame here?) <<I do>> 1/27/10
Hi again, folks,
Please help me with a disease issue I am having! I have done tons of research, talked to my lfs, and spoken to the makers of Mardel products trying to figure out how to treat my fish. Other than water problems being the consistent thread, no one treats the same problem the same way, with the same med, and I am floundering, and my fish are getting sicker.
<Indeed. Almost all fish disease comes down to water quality issues. So that's a pretty safe approach to take when diagnosing and solving problems.
But it doesn't explain all problems.>
I tested all of my water parameters today and everything is good. 4 month old, 75 gal, well planted tank with 2 hang on back filters, pumping 750 gallons an hour. PH 8.0, 0 nitrites, 0 ammonia, GH 18-20, KH 4-6, CO2 at
about 20, (I am using a yeast conductor) Iron at 0. I have used Flourish once, 2-3 weeks ago and again this week, to fertilize, (per instructions)and Flora24, a daily mineral supplement. I do a 30-40% water change every week and vacuum the top layer of gravel. Of the 4 carbon filters, only one was older than a month. It is stocked with 60 inches of fish, Praecox and Boesemanni Rainbows, 5 Congo Tetras, 2 Golden Wonder Killifish, 1 SAE, 2 Bronze Corys, and 3 Blue Rams. I feed a well mixed diet of high color flakes, Cichlid pellets, frozen Daphnia, Brine Shrimp, Spirulina and Bloodworms, and the occasional algae wafers, alternating daily. It's possible I overfeed.
<Not an ideal mix of fish, but unlikely the critical issue here. Why not ideal? Because, for example, Bronze Corydoras want much cooler water than Blue Rams, and again, Blue Rams need much softer and more acidic water than most every other community fish on the market. Picking fish suited to one set of environmental conditions is key to avoiding problems.>
The tank was doing great, fish color was good, my Blue Rams had laid 3 batches of eggs in the tank and 1 batch had already hatched. They have since been moved to my smaller tank to avoid medicating them, and 8 are still alive and thriving. All fish were healthy. Then I went to my lfs to get another pair of Corys, some snails and a Red Marble Pleco because I still have some minor algae growth. This is a well trusted source for fish, mostly raised in-store, or locally raised, and all quarantined for two weeks before they will sell them. I have bought a number of my fish from
them and never had a problem. They are not so good at sick fish, though.
They say they rarely have sick fish.
Within a day of adding the new fish and snails, 2 of my Congo Tetras showed up with what appeared to be a whitehead on their sides. And one of them had what looked like a white fat lip on the inside. That same day one of the Corys died. The other Cory remains completely hidden and I have to keep digging in the tank to chase it out to make sure it's still alive. Also the Pleco looked like a chunk had been taken out of his top fin. Research indicated either true fungus or Columnaris. Since I couldn't accurately diagnose at that point, I didn't do anything immediately, and watched them.
By the next day one of them was showing signs of white cottony growth down his side. There had not been a visible injury prior to this so it didn't fit the true fungus, but since Columnaris will decimate a tank within days,
and all the other fish seemed fine, and it didn't fit those symptoms either, I started treating with API Pimafix for fungus. I continued treating the entire tank for 5 days and saw no signs of improvement , but no signs of additional illness either.
<Pimafix and Melafix are only somewhat useful. Let's be clear here.
Tea-tree oil has a mild antibacterial effect. There are no studies that tell us which bacteria tea-tree oil kills, and which ones it doesn't. So the manufacturers of these products can't give cast-iron guarantees on the efficacy of their products or precisely which diseases they treat.
Moreover, the antibacterial effect is mild, akin to an antiseptic you'd use yourself to clean a wound you gave yourself while gardening. They aren't antibiotics like you'd use to treat gangrene or pneumonia! Tea-tree oil isn't systemic, so won't treat internal infections. In short, it's a VERY limited medication, and some would argue, so limited and unpredictable as to be essentially useless.>
On the fifth day I started adding API Melafix to the treatment, and treated for two more days. There was still no improvement so I knew it was time to remove them from the population and moved the Congos to a 5 gal bucket as the Ram babies were in what would have been the hospital tank. I put in an air bubbler and heater and thermometer, and started treating with a stronger fungus med; Mardel's Maracyn-Oxy(brand new on the market). I
continued treating for 3 more days but the fungus continued to worsen. The folks at Mardel suggested an anti- bacterial addition to the treatment so I have added API EM Erythromycin, a broad range antibacterial med that treats both gram positive and some negative bacterial infections, made for cotton mouth and fungus.
<The problem with Erythromycin is that many bacteria are resistant to it.
Overuse and misuse of antibiotics has caused this. It's a classic example of evolution in action! Anyway, it wouldn't be my first choice. For early stage external bacterial infections formalin and organic dye antibacterials are pretty reliable, if a bit harsh on the fish. One brand I like is eSHa 2000, which works well against Finrot, Columnaris, and true Fungus, all at the same time. For more serious external infections and systemic infections, you often need to use a combination of antibiotics (Maracyn 1 and Maracyn 2 for example).>
It has been another two days and I still see no improvement in the fungus
on one Congo, however the other never got as bad and he appears to be fungus free. It's hard to tell in a bucket. Bad situation.
Unfortunately, I am now seeing fin rot on several of the fish in the big tank, the Pleco being the worse, and I am at a loss as to how to proceed.
Please, do you know what this might be or have any suggestions as to how to proceed? It has been almost 2 weeks since the first sign of illness. I can't believe the 2 Congos are even still alive, but I don't want to lose my whole tank to this.
I so appreciate your knowledge. It is hard to find truly knowledgeable, experienced folks to talk to about fish. And I still have many problems as I am a new hobbyist. Thank you so much!
I neglected some of the other fish observations that you would need in order to help me. (duh) All fish in the big tank are eating well and active. There is increased flashing and darting and some of them have stringy, white feces. I'm concerned about adding penicillin to the big tank for obvious reasons, so if that is necessary, any suggestions to help protect from a recycle would also be welcome.
<Do read here:
I fear you've wasted time with the tea-tree oil treatment, and that's the reason things are getting worse. Cheers, Neale.>

Re: Fungus won't go away and is spreading  -- 1/28/10
Hello Neale,
It seems like I always get you answering my questions. Thank you for your patience.
<Happy to help.>
I read your link and it was very informative, although heavy reading for a novice like myself.
<Unfortunately, microbiology is a difficult topic to simplify!>
I do still have a few questions, if you don't mind. While I was waiting, I began feeding the tank with Gel Tek tetracycline, (the only bottle of Gel Tek I could find anywhere) and most of the fish are eating it. No results yet as it has only been a day. The problem with this is that my bottom feeders, the Pleco and Corys, aren't getting it, nor can I accurately gauge who is getting how much.
<This is the value of hospital tanks.>
The Pleco, actually, doesn't eat anything I feed. Any suggestions for him?
<Move him to his own tank.>
Should I also treat the water simultaneously? I thought I could soak some cichlid pellets in the Gel Tek but usually my top feeders devour those as well. I tried this method with the Congos in the bucket and the pellets are being eaten when I'm not watching, so I don't know if both fish are getting meds, or how much. Also, I am concerned about overdosing as they are bathing in Maracyn-Oxy and Maracyn II. Perhaps I should stop the Oxy, since it didn't seem to help, and use Maracyn I and II only.
<This combination is quite widely used, with some success. But treating internal bacterial infections is hit-and-miss, simply because hobbyists can't diagnose the problem, and only if you know the bacterium involved can you decide on the right medication to use and the necessary concentration.
Here in the UK antibiotics aren't sold over the counter, and it isn't obvious to me that this causes any great loss of fish. The diseases like Finrot that can be treated reliably with most antibiotics can be treated just as well with antibacterials, formalin, and organic dyes. Conversely, the stuff you really do need antibiotics for, most of the internal infections, are difficult for hobbyists to dose, so the success rate isn't terribly high, especially with small fish.>
At this point I am throwing a "hail Mary" pass with these two. What your link didn't address is the issue of water changes while medicating. If one med doesn't seem to be working, should the water be changed between meds?
<In theory, yes. But in practice, organic chemicals like medications will be metabolised by bacteria within 24 hours, so it's usually not an issue either way.>
How much is sufficient. I don't want to waste time trying to draw the meds out with carbon filters.
<Agreed, but waiting 24 hours, and then doing a 50% water change should be sufficient.>
It's very difficult to figure out which meds can be used together, when to switch, etc. I hate putting anything in my tank, let alone adding what seem to me to be massive amounts of meds.
<Yes; mis- and over-use of medications can end up poisoning fish. But that's more of an issue with organic dyes, formalin and copper. Antibiotics shouldn't pose too much of a threat if used as instructed.>
Finally, is it possible for a fish to carry a disease without showing any signs until a stressor happens, and then infect a whole tank? Can snails carry disease that won't affect them, but will affect fish?
<A difficult question to answer. Aeromonas and Pseudomonas are ubiquitous in all aquaria, and only cause problems when a fish's immune system is weakened. They're the equivalent of E coli; mostly harmless to us, but under some circumstances can cause major health problems. On the other hand, Mycobacteria are "primary" rather than "opportunistic" bacteria, and likely to jump from one infected life form to the next. At least some Mycobacteria can infect humans, albeit rarely, so it wouldn't surprise me if a sick snail couldn't carry them too. But that said, most Mycobacteria infections probably do jump from a sick fish to a healthy fish.>
I ask because I need to figure out what is basically wrong, not who to blame. If my water conditions can suddenly turn sour and sicken my fish, I need to know what to fix.
<The problem with Mycobacteria infections is that there's no obvious reason why they cause problems except that connection between stress and a suppressed immune system. "Wasting disease" and "Fish TB" do seem to be a problem with certain species more than others -- Dwarf Gouramis and Fancy Guppies, for example. So while I would reflect on how the tank was maintained, what the fish was fed, and so on, I'd also be open minded about sheer bad luck. Did the sick fish come into the tank infected?>
Can the lead weights that are used to hold plants down cause a problem if not removed?
<Generally no; water changes will keep the lead concentration very low. At extremes of pH this may not be true, but ordinarily lead is harmless because a coating of lead oxide around the lead gets between the water and the lead.>
Can disease come in on frozen food?
<Now this is a VERY good question. Some retailers I have spoken to believe so, having seen Discus, for example succumb to mystery diseases after being fed wet-frozen bloodworms. So they no longer allow wet-frozen foods into their Discus tanks. In theory frozen foods should be relatively safe; while freezing doesn't kill bacteria, it does prevent food going off, and slows down the loss of vitamins. At least some wet-frozen foods are gamma irradiated, and these should be near-100% safe. In short, I use wet-frozen foods all the time, and their benefits likely outweigh the risks, but there may be a small risk attached, especially with foods collected from less than sanitary environments.>
I think that's all the questions I have for now. I can't thank you enough.
Just the peace of mind of having someone who will point out obvious problems that I may not recognize, helps.
<Always happy to chat.>
By the way...love your greeting...Cheers!
<It's very English, I think. But recently I've noticed a lot of Americans using it too. Not sure what the opposite of an Americanism is, a Britishism? Anyway, cheers! Neale.>
one of today's FAQs -- 1/28/10
> Hi Bob,
> There's a question today about (if I recall) wasting disease. Some discussion re: antibiotics, Mycobacteria, and disease transfer through frozen foods. I'd appreciate any comments you have on this, as I'm speculating wildly I fear. Particularly the frozen foods issue: is this something of concern, or merely me repeating illogical speculations made by retailers I've chatted with.
> Cheers, Neale
<I saw this... and have re-read. I too believe that biological disease (mainly infectious, not parasitic) can be/is at times conveyed through foods, including frozen. I also am leery re too-generalized statements re possible bacterial involvements, their treatments in home/hobby systems. W/o culture, sensitivity testing (more time, expertise, gear and livestock, facilities than most anyone has), there is little good to be expected from random administration of antibiotics, as you well know. BobF>

Boesemanni fungus   8/8/07 Hi to the crew, <Hello Lynnette,> I want to thank Neal for his response to my earlier question/problems. (previous email included at bottom of page) I have evaluated my maintenance. I am making a conscientious effort to try to provide the best environment (other than nature) for my fish. <Very good.> After I received the response from Neal my fish did not display the white mouths again until this week. I have kept up with the water changes as previously noted. I have well water that I heat and aerate for a few days before each water change. <Ah, but do you add dechlorinator? This does more than remove chlorine. It also neutralises ambient ammonia (e.g., from agricultural run-off) and locks away metals like copper (e.g., from the pipes). Aerating won't do these things, so isn't a substitute.> My water parameters are the same as before. I have stepped up cleaning my canister filter in hopes that would help. I rinse the bio media in a bucket of tank water every two weeks. The hob filter media is rinsed at every water change. <Don't clean the filter too often. Once a month is probably too often, and I do mine a couple of times a year in some cases. You see, every time you take the filter apart, you stress the bacteria a bit, and you definitely run the risk of cleaning away the bacteria. The sign to clean a filter is when the flow of water is obviously less than before. Otherwise, leave it be.> Since the fungus symptoms have returned I am ready to medicate the fish. From my research it looks like sulfa meds are the med of choice? My local fish store is Petco and I don't trust them to recommend medications for my fish. Is there a drug that would be better suited? <Here in England I'd use Interpet combined Finrot/fungus, but in the US your options seem to include things like Seachem Sulfathiazole and Mardel Maracyn. Just don't either "tonic salt" or new-age cures like Melafix or Pimafix. None of these are consistently effective.> I also would like to know if I could treat the whole display tank since 14 of the Rainbows show varying degrees of small white tufts on their mouths? <Always always always treat the entire tank with something communicable like this. This holds true even if you have to remove a sick fish to a hospital tank.> I know this isn't the best choice but I don't have a quarantine tank large enough to treat all at once. I have quite a few plants in the main tank ,Corydoras and the Pleco. I considered moving out the Corydoras and the Pleco but I honestly don't know if I could catch them out without tearing the whole tank down. What's your opinion/recommendation? If I treat the main tank should I remove the plants? <The cats and the plants should be fine. Check the medications available against the information provided on the packaging or the company web site. I don't have experience of those American brands so can't speak personally. But generally, as long as you follow the instructions to the letter (and remove carbon from the filter) medications are safe and effective.> Trying to figure out how to do this so all fish that need treated are treated and the catfish aren't negatively affected. <With cats, it is specifically copper and formalin that are suspected to cause problems for them. I've never found that to be the case, but then playing Russian Roulette once and surviving doesn't mean its a safe game!> I appreciate all the time, patience and knowledge that is put into this web site and the responses to questions. I totally respect all of you. <Cool. And thanks for saying so; I'm sure we all appreciate it.> Thanks for helping, Lynnette <Good luck, Neale>

Re: Boesemanni fungus -- 08/08/07 Thanks to Neal for his help. I have another question for Neal or someone to help me with. After I medicate my 55 gal tank with the sulfa what kind of aftermath can I expect as far as cycling again. I have a full bio load now and fear what the ammonia and nitrite spikes will do to my fish. What can I do to make sure my fish make it thru till the tank is stable again after the medication? I appreciate your help.. many thanks. Lynnette <Hello Lynnette. While I can't verify this from experience (sulphur drugs are not sold over the counter in the UK) my assumption is that provided you follow the directions on the package, your biological filter should not be harmed by aquarium-specific drugs. Having said that, I'd still remove 33% of the filter media and keep it alive in a bucket of untreated aquarium water by bubbling through some air via an air pump and airstone. That way, if something does go wrong, you can do a 90% water change and then restore the filter to near-normal output by putting the "saved" filter media back in. Regardless, visit the web site of the drug you intend to use, and read up any FAQs they have online. Most of the big aquarium drug companies have this information online. Cheers, Neale>

Fallow tank (and more!), FW infectious disease...    8/6/08 Hi Crew! I have a few different things to write in about, but if I remember correctly, you prefer them all in one email. Sorry in advance for the length, but more info is good, right? <Up to a point...> There's a previous reply from Neale below this email, since unfortunately I'm writing in about the same thing again. After the Betta and African dwarf frog died, my tank was empty of fish (and frogs) for probably six weeks total. I didn't end up adding any medication to the empty tank, on the idea that, like Neale said, there will always be "harmful" bacteria floating around at "non-harmful" levels until a fish is injured or stressed enough to become susceptible to infection. <Correct; Finrot (or Red-leg in the case of amphibians) is a response to environmental problems rather than a disease that creeps into the tank unseen.> I didn't want to wreck the good-bacteria system, so instead I did large water changes and added three male guppies. <Do remember fancy Guppies are NOT HARDY. They are very delicate fish and should only be kept in clean, mature aquaria. Small tanks aren't suitable because you can't keep water chemistry/quality stable easily in them.> One of them died after a run-in with the tank vacuum--my fault. I'd had the other two for about six months when one of them started looking a little large in the belly. He was more aggressive and usually got more of the food, so I thought maybe he was just getting a little plump. After about a week the swelling had only grown, and the other fish looked perfectly healthy, so I separated the swollen one and put Epsom salt in his water for a week, thinking maybe he was constipated. That didn't help, so I treated him with two rounds of Jungle Fungus Clear (Nitrofurazone, Furazolidone, potassium dichromate). That didn't help either, and like the Betta he soon got the pinecone look and died. By then the remaining guppy was looking swollen too. <That a succession of fish are dying from fairly generic symptoms means just one thing: environmental problems. This tank is, for whatever reason, not conducive to the long term health of fish. Tanks 10 gallons in size are not recommended for beginners, and anything smaller than, say, 8 gallons is not suitable for fish at all, except perhaps a single Betta. These 2 and 5 gallon tanks you see on the market are essentially worthless, being accountable for the deaths of VAST numbers of fish.> I changed the filter and removed the carbon, and added the medication and the Epsom salt right to the tank, hoping that if the medication is capable of nuking whatever this is, I might as well add it to the whole tank, as I probably should have in the first place, as Neale suggested. I added the Epsom three days ago (1 tsp/5 gal), and the medication two days ago. There's been no improvement. Today I added more Epsom (1.5 tsp/5 gal) and a little more medication as the water was looking lighter (the medication turns it blue). I figured the fine gravel substrate might be absorbing some of it. <You really can't "nuke" a tank hoping to get rid of all the problems except by sterilizing it, and that will of course kill the biological filter. This is why healthcare is a two-step process: first you ensure ideal conditions, and second you identify and disease and only then treat with an appropriate medication. Randomly adding stuff like salt, Epsom salt, Methylene blue or whatever in the hope of killing whatever is in the tank just doesn't work. Never has done, never will. It's the same reason your doctor asks for your symptoms before prescribing a treatment -- only the right medication will help, and the wrong ones could cause more harm than good.> It's a 2.5 gallon tank, 79 degrees, with aquarium salt at 1 TBSP/5 gal. 25-30% water changes weekly, live plants, one painted acrylic tank decoration (the paint is not wearing off), compact fluorescent lighting, in-tank Mini Whisper filter. The guppies ate whatever algae they could find in the tank, and flake food, as they rarely seemed to recognize anything else (bloodworms, Tubifex worms, algae wafers) as food. <This tank is just no good for fish. End of discussion, and no further treatment will help. A tank this size simply isn't viable for fish. By all means add some Cherry Shrimps and novelty snails that don't breed, such as Nerites. But nothing else. The Cherry Shrimps will have babies and provide lots of entertainment value as well as being brightly coloured. Please, please trust me on this.> My best guess is that the same thing happened to all three fish, and I'm assuming it's an internal bacterial infection. <No; "internal bacterial infection" is (in my book at least) the term most commonly used by fishkeepers who don't want to face facts. It's really very simple: in a tank this small the filter can't process waste fast enough to keep the fish healthy. The water isn't sufficient to dilute the ammonia and nitrite adequately that these don't poison the fish. There isn't enough water to dilute the organic acids that accumulate between water changes. The volume of water is too small to keep temperature stable. The surface area is too small for oxygen to diffuse in quickly enough to satisfy fish. There is really, HONESTLY no way this tank will keep fish for anything more than a "death row" sort of existence.> The medication that I have does not seem to be making a difference. Do I need to try a different treatment? <Nope; different tank.> Is it too late for treatment by the time the swelling has gotten bad? <Likely, yes; with small fish by the time abdominal swelling occurs the internal organs are damaged beyond repair.> I certainly could've stepped in earlier with the medication, but was hoping it was just constipation or too much food until it was obviously a different problem. <"Hope" is adequate for football games, but where animal welfare is at stake you have to be a bit more proactive. Any book on Guppies would have told you that they need a reasonably big tank (at least 10 gallons, and I'd recommend at least 20 gallons because of their delicacy and aggression). So your first mistake was not reviewing their needs and then putting them into a tank woefully small.> Do I need to put the little guy out of his misery at this point, or do you think he has a chance? <I don't think any fish has a chance in this tank. I honestly can't in good conscience recommend you add/buy any more fish until you've bought at least a 10 gallon system and ideally a 20 gallon system.> He's behaving as though he's perfectly fine--he's always been very active--but the swelling is very noticeable and has not gone down at all. I skipped feeding him last night because I was worried over putting anything else in his stomach with all that swelling. He has a healthy appetite and there's no pineconing. <OK.> In other news--my brother has a Betta in a similar setup, with no salt. He's around three years old now and I know that's quite old for a Betta. He's developed a lump under his scales, about a third of the way down his body, on the left side only, and the scales over it are protruding. His right side is perfectly smooth. I added Epsom on the off chance it was a blockage or that it was swelling that could be alleviated, but it hasn't improved much if at all. My educated guess says it's a tumor, since he's old and the lump is only on one side. I'm assuming there's nothing to do for him, but I figured that while I was writing in, I'd ask if there was. <Would tend to agree; 3 years is about the going rate for a well cared for Betta. I notice (with appreciation!) the lack of salt. As I have said MANY times, salt has no place in freshwater fishkeeping except for specifically treating certain diseases in the short term.> And, lastly, I'm babysitting a roommate's goldfish for the summer. He came to me in a quart-sized bowl. I don't have the resources to gift my roommate with the 10+ gallon filtered tank the goldfish should be living in, but we did get him an acrylic bucket-shaped (more surface area) container of about 1.5 gallons. <Goldfish need more than 10 gallons, at least 30, and 1.5 gallons is simply cruel. This poor fish will be dead well before its time. Make sure your friend understands that what she's doing is animal abuse; if you can't have bigger tanks in your apartments, then don't keep fish. If you want to own and care for an animal, then meet its needs. There's no "in between" situation that lets you rationalise away slowly poisoning a Goldfish with its own filth, which is what's happening here. I find it strange that people in the UK and US will be horrified at reports of people in Korea eating dogs or the Spanish fighting bulls, and yet have absolutely no qualms at all about exposing the poor Goldfish to years and years of torture and poisoning. Quite bizarre.> I think he's a comet--upper third is orange, the rest silver/light gold, just shy of 2" nose to caudal peduncle. <Ah, the Comet... one of the varieties best kept outdoors. It's a fast, active variety, apparently developed in the US of A. Deserves better treatment than this.> She had the fish for about four months before I got him. I'm hoping his growth hasn't been completely stunted and that he'll get the benefit of a little more breathing room. <Hmm... a marginal improvement at best, like getting to choose between the arsenic or cyanide really.> In the meantime--his "bucket" has the same fine gravel that I used for the guppy and Betta tanks. It's definitely small enough to fit in his mouth, and he likes to pick the pieces up and spit them back out, which as I understand it is typical goldfish behavior. I've never seen him swallow one, but I'm worried that if he did, it's large enough that he wouldn't be able to pass it. Is he a gravel-swallowing case in the making, or should I leave well enough alone? <Goldfish sometimes do choke on coarse gravel, but pea gravel and better yet sand is absolutely ideal for them. They sift the substrate with their teeth (in their throats) and gills, and then spit the sand out. Any sand that carries on into the gut comes out the other end just fine. It's what they evolved to do.> Thanks, for the umpteenth time, for everything you all do--I've been visiting, searching, and reading the site for two and a half years now, and I don't know what I'd do without such a great resource. It's like having a good textbook that you can query! <I'm glad we're able to help.> Look forward to hearing from you, Rachel <Hmm... not sure you'll be too pleased with my analysis, but it's accurate and honest. The best I can do in this situation. Your move. Cheers, Neale.>

Is fungus infectious?  2/1/08 Thank you so much for providing such a great website! I have a relatively new 30 gallon freshwater tank, I use API Tap water conditioner and Jungle pH Buddy regularly. I cycled the tank using Bio Spira, and all the readings were optimal before I slowly added fish and plants over a couple of weeks - I continued adding bio Spira each time I added new fish to help ensure the tank could cope with the new bio load. I have an emperor 400 bio wheel filter, and the temperature is a constant 75F. My tank community consists of 2 3-spot gouramis (added first), then 2 dwarf gouramis, one spotted Pim, one red tail shark (I read up on compatibility (water and temperament!) plus adult size so the tank wouldn't be crowded), plus several spiral Val.s, baby ruffle swords and sword plants. Everything was fine, and I test the water every day and readings were all within desirable parameters. However, yesterday morning I noticed a small bump on the top of the head of one of the dwarf gouramis, it was white and fuzzy, and I think from reading your site it could either be fungus or columnaris. I didn't have a quarantine tank and had to get to work, thinking I could rush home, jump in the car, buy a small tank etc and medication to set-up quarantine when I got home. Alas, when I got home, the fungus-like fuzz had spread over almost all the head and one eye, and my little fish died within minutes. Really very upsetting, and I feel awful. I tested the water with my API master kit and readings are as follows: pH 7.5, Nitrite 2.0, Nitrate 40, Ammonia 1; temperature still 75F. After removing the dead fish I added a shot of Bio Spira to boost the bacteria, and my remaining 5 fish all seem perfectly happy, although I didn't feed them as I was conscious of the fact the nitrite and ammonia was a little high. Sorry to be so long winded - but my questions are: will the fungus affect the other fish? Should I treat the water with some sort of medication to ensure it won't come back? Because whatever it was killed my Gourami so quickly, I'm really paranoid that the other fish will suffer the same fate. What should I do to prevent this? Thank you so much for your help, I really appreciate your time and expertise, and apologise again for the long message. All the best, AJ <Greetings. The short answer is that fungal infections are not directly infectious. However, because fungal infections are commonly associated with environmental issues such as poor water quality, if you see one fish with fungus, there's every reason to imagine that the others are at risk as well. Hence the need to treat all the fish, not just the one with obvious cotton wool-like threads (which is what Fish Fungus looks like). I would eschew Melafix-type things in favour of standard anti-fungal medications of which there are many. Now, all this said, there are some issues for you. Your ammonia and nitrite levels are insanely high. Too many fish in too immature an aquarium. While I respect the fact you used BioSpira, that isn't carte blanche to just add a whole bunch of fish without thinking any more than simply passing your driving test makes you a good driver. What you SHOULD have done was add one or two very hardy fish, such as one or two female Trichogaster trichopterus (the males are very aggressive and not worth keeping in small community tanks). You'd then let the tank run for the next few weeks, testing the nitrite and ammonia levels every few days. If things stayed good, i.e., those tests came out at zero, you'd add a couple more fish, and so on across a two or three month period. A two-week period for adding everything simply isn't acceptable, and certainly not if you have an ammonia reading of 1 mg/l -- that's basically lethal to fish, and your stock will soon be dead. What else? Colisa lalia is a fish I cannot recommend anyone keeping, and the specimen you had with a blister on its head could quite easily have died from the dreaded Dwarf Gourami Disease, a virus with no known cure. The virus is found in over 20% of the Colisa lalia exported from Singapore and is incredibly infectious, meaning that practically every Dwarf Gourami on the market is likely to be infected by the time you go shopping for them. Buying these fish is a waste of money, frankly. Next up, there is not much chance that your Epalzeorhynchos bicolor is going to be a good idea in a 30-gallon tank. These fish are very aggressive and territorial, and at minimum they need a tank 100 cm in length before they become even close to tolerant of tankmates. So, to summarise, I suspect you have too many fish in a tank that is too immature and/or are chronically overfeeding. I wouldn't put any money on the Colisa lalia living long, and the Epalzeorhynchos bicolor will gradually become more annoying as it matures (that's if it doesn't jump out, of course). I suppose I should make the point Pimelodus pictus is a *schooling* fish that should be kept in groups of at least three specimens, but your tank is not a good place for this species right now and I'd not expect your specimen to last for much longer. Hope this helps, Neale.>

Re: Is fungus infectious?  2/1/08 Thanks for the candid feedback; there is just so much conflicting information in books and on the web, that it's really difficult to know what to do. I'll treat the tank for fungus, and do my best - so far there are no signs of distress from the fish, but your advice is well heeded and I'll keep you posted. <Ave! Glad the information was useful. Good luck to you and your fish, and please get in touch if things don't improve. Cheers, Neale.>

Fallow tank, Dropsy, FW, Infectious Dis.  11/25/2007 Hi Crew, <Hello Rachel,> Here I am writing in yet again! About a month ago I lost both the Betta and the African Dwarf frog in my freshwater tank to bacterial infection. The frog had mildly injured its nose and one of its hands, probably by diving into the gravel at high speed the way he was fond of doing. I'm guessing one or both wounds got infected. He developed dropsy, and he died despite quarantine and treatment with hydrogen peroxide, Neosporin on the wounds, and even a needle aspiration to help take the pressure off his internal organs (all of which I researched before trying, of course--and the needle aspiration, while a little drastic, did seem to help him perk up and fight a few days longer). I did my best to keep the tank extra-clean to keep the Betta healthy, but I suspect he'd already been infected internally for awhile--he got dropsy too, and by that time I'd gotten my hands on some antibiotics (the local pet store closed, and as I'm a university student with no car, it took awhile to get any from further away). But, despite those in combination with aquarium salt, he died too. <Oh dear.> It's my understanding that it's pretty hard to nurse a creature back to health once it's developed dropsy, so although I'm sad they didn't make it, I tried my best. <With small animals, yes, this does tend to be true. By the time dropsy is apparent in them, the internal organs have been damaged beyond repair.> (The Betta was two and a half years old, too, which I hear is not too shabby a lifespan.) <In the wild they are basically annuals. In captivity, some people get the odd Betta to last 3 or 4 years even.> If you see anywhere that I went wrong with in trying, please let me know! My end point in writing is to ask about the tank now. It's been fallow for three or four weeks, just live plants and probably some limpets still left in there. Would this have been a bacteria that would've died with no host, or is it still floating around in the water? <To some extent the bacteria will still be there. Secondary infection-causing bacteria are largely bacteria that potter about harmlessly at all times, and only become a problem when wounds allow them to enter the fish. Think about things like E. coli in humans: absolutely harmless and indeed essential where they live in the lower intestine. But if they happen to get somewhere else, like the urinary tract, they cause potentially harmful infections. It's the same with the Finrot bacterium Aeromonas hydrophila (which causes Red-leg in amphibians and stomach upsets in humans). Normally it does its thing in the water, feeding on whatever organic matter it finds. On a healthy animal, the immune system has no problems killing it off. But when an animal is weakened, e.g., by the damage caused by ammonia in the water, the immune system cannot function 100%, and the Aeromonas hydrophila overwhelm exposed tissues where they feed on proteins, particularly haemoglobin. In other words, assuming your new livestock are happy and healthy, then the bacteria likely won't cause any major problems. Disinfecting the tank is certainly one option, but you would have to cycle the biological filter again. Even in this case, bacteria will get in eventually anyway. They just do, and trying to fight against bacteria is usually a waste of time because they run this planet, not us, whatever we might like to think. So far better to accept the bacteria for what they are -- opportunists that will take advantage of any situation they can -- and simply focus on keeping healthy livestock that can deal with the bacteria naturally.> I'd gladly scrub the tank down, but haven't yet as I was hoping to keep the beneficial bacteria going. I didn't want to put anything else in there if there's a chance of a latent bacterial population lurking around. <The bacteria will certainly be laying around in the water and substrate and filter media. Running a course of anti-Finrot/anti-Fungus medication won't do any harm, and might be worth a shot in this instance. Do also bear in mind the filter bacteria will have died back in the interim because of the reduction in ammonia for them to "eat". So before adding new livestock, you may want to add an ammonia source for a week or two first, to get them back into fighting fettle. Adding a pinch of flake per day, or leaving a bit of seafood to decay at the bottom of the tank, should do the trick. The bacteria don't care where the ammonia comes from, and if its from bacterial decay of uneaten food, that's fine with them. Obviously test for ammonia or nitrite afterwards to make sure everything is working before you add new fish.> Thanks for being there as always, Rachel <Hope this helps, Neale.>

Tail/fin rot, guppies    8/26/07 Hello. I just stumbled upon your website and noticed it is very helpful. I have had a fishtank for a while but just got a new one with new fish. It is only a ten gallon. I have a guppy who developed tail/fin rot, and it seems to be spreading to my favorite guppy. I don't know if it is though. I'm just trying to confirm my observations when i ask: is it contagious to my other fish besides the guppies? Thanks a lot. -Adam <Hello Adam. Thanks for the kind words. There's two ways of looking at your question. If you're asking will Finrot jump from one fish to another the way a cold jumps between people, no, not really. The bacteria that cause Finrot are (probably) present in all aquaria at all times, and only under certain circumstances do they actually become a problem. However, if your question is "one of my fish is sick, will the others get sick too?" then the answer to that is yes, most likely. Finrot bacteria become problematic when the immune systems of your various fish become compromised in some way. Two factors are usually at work, poor water quality and physical damage. They can work independently or together. With guppies for example Finrot can start when they're kept with nippy fishes such as serpae tetras or black widow tetras, both of which view guppy tails as food. Or alternatively (and more usually) water conditions in the aquarium have dropped below a certain threshold, and the guppies no longer have the strength to stave off infection. In the case of guppies, ammonia and nitrite are dangerous, but so too is a low pH (anything below 7.0) and a low hardness (basically you want "moderately hard" to "very hard" water chemistry). So, if you have multiple fish showing signs of Finrot, and can rule out fin-nipping, then study the conditions in the aquarium. Do water tests for ammonia, nitrite, pH, and hardness (ideally KH but GH will do). Oh, and if the water conditions are so bad the guppies are getting sick, the other species are likely be stressed to some degree, too. Hope this helps, Neale>

Re: tail/fin rot -- 08/26/07 It turns out that my water is too soft. Thanks for the advice. -Adam <Cool. Bump up the carbonate hardness especially. That's the bit livebearers appreciate. Adding "tonic salt" -- whatever the retailer might say -- won't help. Cheers, Neale>


White "fuzzy" growth, FW   6/4/07 We just added two new fish to our established aquarium last week. We noticed the other day that the Gourami that we added has some sort of fuzzy white growth mostly on it's bottom fins, but has a spot or two on it's top fins. We've dealt with ich before, but this is definitely different. <Almost certainly fungus or mouth "fungus". Ordinary fungus looks like long white threads and has a similar appearance to fungal mould. Mouth fungus tends to be greyish, the threads are shorter, it looks slimy, and it is caused by a bacteria, not a fungus, despite the name. Either way, you need to treat the aquarium at once. Anti-fungal remedies are available and many treat both kinds of disease in case you aren't sure which you have. Regardless, fix the cause as well as the symptoms. Ordinary fungus may be caused by physical damage (it's similar to gangrene in humans, basically an infected wound) but both can be caused by poor water quality. Check nitrite/ammonia, water chemistry, and reflect on your maintenance regime.> > More strangely, we've noticed that one of our mollies that we've had since we started the tank seems to be eating off of the Gourami -- doesn't seem to bother it. This same molly has just in the past 2 days become quite aggressive towards all of the fish in the tank except for the Gourami. <Mollies can be aggressive, especially when kept in small groups. For many reasons I don't really rate mollies as community fish, and this is one of them. They're great fish, but best kept on their own in a nice sized school in brackish water. Anyway, there isn't much you can do to "fix" this, beyond removing the offender to another aquarium. Your molly is equipped with rasping teeth that it uses for its normal diet of algae. If such a fish persistently scraped at another fish, the result for the poor victim will be loss of skin mucous and eventually skin damage. So you need to nip this problem in the bud.> > Can you give me ANY advice or information on what might be going on? This is my 6 year olds tank, and I hate to see any losses, considering we've finally had a few good months following our ich difficulties! <Male mollies are aggressive, and will threaten all sorts of fish. I've seen Sailfin mollies threaten Australian rainbowfish, for example. It's a hard-wired behaviour and there's zero you can do about it. In a large group of male and female mollies it doesn't matter and actually adds to the charm of these fish. But if you have one particularly aggressive molly in a community tank, it can be disruptive. Adding additional mollies to create a group of six or more might help, but my caution here is that the lifespan of mollies in freshwater aquaria is not high. They need (at least) very hard and alkaline water with zero nitrates, and are simply easier to keep in brackish (or marine!) aquaria. This really comes down to a simple fact: not all fish sold as good community fish by retailers are actually good community fish at all. One random thought is diet. Are you providing any greens? Mollies should be eating 75% green foods and 25% regular foods. Blanched lettuce, thinly slice cucumber, spinach, Sushi Nori, algae from a garden pond, vegetarian flake food, and algae wafers should all be the standard foods your mollies get. Without these foods, they *may* be sampling alternatives for want of their correct diet. Try adding more greens and see if that helps.> > Thank you so much! > Suzy <I hope this helps, Neale>

Re: white "fuzzy" growth -- aggressive molly  6/4/07 Thank you so much, Neale! <No problems.> > I teach, so I can't get out during the day, but we'll be on our way to get treatment for the tank as soon as school gets out! <Very good.> > I have a small 3 gallon tank with a running filter in my classroom that houses a male Betta and one other tropical fish that another teacher "donated" - I'm not sure what it is -- clear colored with horizontal black stripes. Is it possible to put the molly in that tank, or will he also likely be aggressive towards the Betta and the other fish? If I do have to "get rid" of him, what's the best way - most humane - way to do that? <No, the molly wouldn't work there at all. I can't really condone destroying a fish because it's inconvenient -- that's a case of the fish being punished because the human didn't do any research. Very bad karma indeed. The correct thing to do here is find him a new home. That shouldn't be difficult at all. Many aquarium shops will take back unwanted fish. Alternatively, set up a 20 gallon tank just for mollies! In a school situation they'd be great -- a group of mollies will breed happily, and in brackish water are *extremely* easy to care for. The baby mollies are fun for children, giving them a chance to see animals being born and growing up on a relatively fast timescale (a few months). Such a tank needn't be difficult or expensive to set up. You don't need lights, for example, and simple air-powered sponge or undergravel filter will take care of filtration perfectly. Cheers, Neale>

Fin Decay in New Tank Hello. One of my new platy fish has fin rot, which I am currently treating with MelaFix. I was told to remove the carbon filter while treating (one week) and replace the filter with carbonless polyester fiber. I have done that, but am wondering if I can put the same carbon filter back in once treatment is completed or do I have to buy a new one?  The tank is currently cycling (two weeks old).  Thanks in advance for your help, LittleTank in Louisiana <Hi LT in L, Don here. Nope, you'll need fresh carbon. Activated carbon "fills up" and becomes inactive carbon very quickly. Within a day or two. I'm just wondering if you have a bacterial fin rot or poor water conditions since the tank is so new. I would discontinue the Melafix and just do large daily water changes. Ammonia can build up in a new tank causing the fins to "burn". Testing for ammonia, nitrite and nitrate would reveal the answer. If you do not have a test kit, I strongly suggest you pick one up. Your LFS could also do a test for you>  

White slime coat What is a very fine white sheen that seems to be in the slime coat and seems to only cover portions of body? <Possibly a bacterial infection, perhaps a reaction to poor water quality... rarely a true fungus> I know ich and it is not that. I lost 20 cichlids in my 150 gallon tank with sump and gravel filtration. It was stocked with electric blue, a variety of peacocks, and red empress which were over a year old that I had raised together since they were 1" fry. One day I noticed a white spot on the eye of a female red empress. It grew larger the next day, so I checked with the LFS and they gave me Amoxicillin for Popeye. I gave four treatments every other day over seven days. The eye cleared up at the end of treatment, but most of my cichlids developed a very fine white sheen over parts of the body, mostly on the side of the body and some had it around the head also. Ph was 8.0, Ammonia was .5 ... <This is definitely a problem... toxic by itself at this concentration... the antibiotic killed off your nitrifying/biological filter> ...and the fish were hanging at the top of the tank and had a very poor appetite. I put my carbon filter back, did a 30% water change and added Amquel to remove ammonia. The next day the fish began eating and acting fine again, but the white sheen continued. Two days later the Ammonia went up to 1.0  <... yes, the fishes continued to produce/excrete ammonia...> and the pH dropped from 8.0 to 7.8. I vacuumed the gravel and added stress coat. The next morning all 20 of my 3-4" beautiful cichlids were dead on the bottom of the tank. I checked the ph and it was 7.4 with ammonia at .5. My tap water is 7.6 from a well. I'm sure the pH change and obvious crash of the tank killed the fish... <Yes, I agree> ...but I don't quite understand what caused such a drastic pH change and would love to know what the fine white sheen was? <All likely related... the pH drop was consequent to general decomposition of the dying filter biota, fishes... the sheen a chemical reaction of your fishes to the high ammonia, drop in pH... bought on mainly by the antibiotic killing off your bio-filter> Side note: They did extremely well all year with many females reproducing. I cleaned out all the dead fish, rocks and plastic plants; surprise of all there was one little peacock fry swimming at the surface. He is now in another tank with all the fry produced from this tank of cichlids.  <Am sure you see the logic now of not treating ones livestock in their main/display tanks, and the meaning of the word "anti" (against) "biotic" (life). Bob Fenner>

Re: White slime coat, FW - Update I got the answer to the fine white sheen. Chilodonella. <Maybe> I took a dead fish to a local wholesale fish breeder and he checked it out. I also read where Amquel can produce a rapid drop in pH. <Yes, in marginally, poorly buffered water> I had added some the night of the crash. Yes, I learned a few hard lessons, hopefully the next generation of fry from their departed parents will not suffer from my ignorance. Thanks for the response. <Thank you for your update. Bob Fenner>

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