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FAQs on Freshwater Infectious (bacterial, fungal) Diseases: Identification, Diagnosis

Related Articles: Freshwater Fish Diseases, Freshwater Diseases, FW 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: Causes/Etiology/Prevention, Cures/Medications, Case Histories: Bacterial, True Fungal, & By Type/Organisms: Fin & Mouth Rot, Columnaris, Mycobacteria/Tuberculosis, Whirling Disease, Bettas w/ Infections,

Fungus on some fish /RMF    11/3/14
Hi I wrote to you a few months ago about my large Silver Dollar who suddenly developed pop eye & fungus patches. Despite my best efforts he died.
<Am jumping in here; though Neale likely was corresponding with you. He'll see this when the sun comes up in Europe>
Within the past few weeks I noticed fungus appearing on at least 4 other fish and I am beside myself as I have beautiful large, expensive fish in this community tank. Went to a local guy who gave me a white powder to put in (unfortunately I didn't get the name but was told to keep it refrigerated).
<? What is this I wonder>
It is now 10 days later & I don't see much of a change & the tank is overdue for a water change. I keep the temp at 78 & check the Ph regularly & maintain it at approx 6.8.
<.... Ammonia, nitrite, nitrate? RedOx?>
Anything you could suggest would be greatly appreciated.
Rita~
<When, where in doubt, serial water changes... Send pix and data. Bob Fenner>
Fungus on some fish /Neale    11/4/14

Hi I wrote to you a few months ago about my large Silver Dollar who suddenly developed pop eye & fungus patches. Despite my best efforts he died.
<Oh dear.>
Within the past few weeks I noticed fungus appearing on at least 4 other fish and I am beside myself as I have beautiful large, expensive fish in this community tank.
<As Bob F stated, without information about the aquarium hard to make useful suggestions. As always with freshwater aquaria, check nitrite first of all (as a test of water quality). Most fungal and Finrot infections are
opportunistic. Physical damage (e.g., from rough handling or fighting) plus non-zero ammonia and nitrite levels is (overwhelmingly) the commonest scenario.>
Went to a local guy who gave me a white powder to put in (unfortunately I didn't get the name but was told to keep it refrigerated).
<Presumably an antifungal. Methylene Blue is the oldest remedy for fungal infections, but there are many (some better/safer). But invariably remove carbon from the filter, if used, otherwise medications generally won't work.>
It is now 10 days later & I don't see much of a change & the tank is overdue for a water change. I keep the temp at 78 & check the Ph regularly & maintain it at approx 6.8.
<Do of course review the pH, hardness and temperature are appropriate to the species being kept. Rainbowfish and livebearers, for example, will get fungus infections in acidic conditions.>
Anything you could suggest would be greatly appreciated.
Rita~
<Hope this helps. Cheers, Neale.>
Re: Fungus on some fish     11/5/14

Neale and Bob ...thanks so much for your responses & Bob it was you I corresponded w/ about the SD back in early July this year.
What are "serial water changes?"
<A quick succession of water changes; not so much temperature and water chemistry are dramatically changed, but enough to rapidly dilute any problems. Typically, 20% once or twice a day works well,
certainly leave a few hours between water changes. If you can keep water chemistry and temperature steady, then changing 50% at once is worthwhile. Basically, the idea is to change as much of the water as possible, as frequently as possible, so that any stress factors (such as ammonia, nitrite or nitrate) are diluted away.>
The med I was given sounds like lovosmel phosphate (sp?) & the 1st round we did not remove the carbon but have done so now.
<Good. Almost always, if you leave (viable, fresh) carbon in the filter, then medications have reduced/no effect.>
Don't have a nitrite test kit (never needed it) but will get one now.
<Together with pH, nitrite is the key beginner's chemical test kit, and arguably the one every (freshwater) fishkeeper should have even if they don't own any others. Less confusing than ammonia (because false positives thanks to chloramine are common) and more immediately relevant to health than nitrate (which can largely be ignored if you stock moderately, feed moderately, and do regular water changes).>
A friend suggested we strip the tank, tossing the plastic plants & bleach the decos, what do you think of that??
<Possibly, and won't do any harm, provided you don't strip the filter.
Leave the filter running, remove rocks and ornaments so you can give them a good clean under a hot tap (bleaching isn't really necessary though), then stir the gravel so you can siphon out more of the dirt than otherwise. Deep cleaning a tank rarely/never fixes diseases, but can help reveal problems such as dead/rotting cadavers that are causing excessive water pollution.>
Attached are 2 pics of the most affected fish (lavender gourami). I have a few baby clown loaches & see them after the fungus.
Many thanks,
Rita~
<Would actually wonder about Costia being the problem here. Sometimes called "Slime Disease" because affected fish develop larger than usual amounts of grey slime on their bodies. Various commercial medications are available, usually containing formalin. Use very carefully as directed because some fish (e.g., Loaches) respond poorly to these formalin. Look out for signs of stress such as gasping at the surface. Alternatives are
available. In the UK, I've found a medication called eSHa EXIT works quite well on Costia, especially alongside seawater dips. Conversely, avoid "cure-alls" such as Melafix that generally don't cure anything. Cheers, Neale.>

Re: Fungus on some fish     11/6/14
Neale, thank you so much for your detailed response. When I began fishkeeping 30 yrs ago I did have all the test kits but never had an issue w/anything other than pH.
<Indeed?>
Because I am disabled and need help doing stuff, typically 50% of the water gets changed every 4 weeks but because of the meds we're about 2 weeks overdue!
<Ah, well, best get on it this weekend!>
I will keep you posted. Thank you again.
Rita~
<Glad to help. Cheers, Neale.>

Re: Fungus on some fish      11/7/14
Ok got the test kits, no nitrites but nitrates were a bit high, pH perfect.
<Good.>
Did a 50% water change (nitrates better), deep cleaned tank, threw out all old plants, washed & put in new decos & will do smaller water changes every other day for the next week & basically hope for the best.
<Sometimes all you can do/need to do.>
Thank you again.
Rita~
<Most welcome. Neale.>

What's that? 5/10/11
Hi,
<Hello>
My children and I were looking at some of our water through my son's microscope. Found this. Would you identify it for me? Thanks.
Jeff
<Looks like the edge of a bit of wood, plant material... "Cells" from the early microscopists' views. Bob Fenner>

Differential diagnosis of mechanical fin injury, nipping, and disease 4/30/11
I've searched this site, other sites on the net, and many books, but I've found only a few vague guidelines to this question, so I'm wondering if anyone can lay out some specific characteristics for distinguishing between mechanical injury to fins from tank contents, nipping, bacterial fin rot, and fungus infection. Thanks! I love this site.
Tim
<You can't be 100% sure about the source of fin damage. But generally, biting or fin-nipping produces clean, oval or circular perforations to the fins. At the edges of the fins these will be usually be semicircular. Such fin damage looks clean and, under good environmental conditions, generally heals by itself with no need for medicating. Healthy fish can prevent bacteria infecting damaged fins. To some degree, many fish *expect* to get nipped periodically, and wild fish have evolved strategies to deal with this, perhaps most famously the eye-spots on the caudal peduncle of many fish that confuse fin-predators over which end of the target fish to aim for (Oscars have these for example, to deal with characin fin-predators including Piranhas). Finrot is caused by bacterial infection of the fins, typically because the fish is stressed somehow. Poor environmental quality and lack of the rights sorts of food are the two most common reasons fish lose their healthy immune system. Initially fins develop white patches or specks where opportunistic bacteria have entered the fin membrane. These usually become pink as blood vessels become blocked, and eventually it's the lack of blood supply that causes the fin membrane to die, hence the tears and holes in the fin. If you see both dead white areas and holes in the fins, then Finrot is probable. Other common symptoms include bloodiness to the fin, lack of vigour in the fish more generally, and very often unusual behaviours such as shyness, lack of appetite, etc. Fungal infections are very distinctive thanks to the white hyphae that resemble cotton wool. They rarely occur on healthy fish, but commonly follow on from fin damage (include Finrot) in water where the environmental quality is low. Cheers, Neale.>
Re: Differential diagnosis of mechanical fin injury, nipping, and disease 4/30/11
Neale - Thank you! That was very helpful. I'd seen hints of most of the things you said, but I like hearing these rules explicitly stated by an expert.
It would be a pity to misdiagnose something so important and treat ineffectually.
Tim
<Glad to help. Yes, it's important to get the situation right prior to medicating, but note that some medications treat both Finrot and Fungus, and used appropriately, these shouldn't normally cause harm to healthy fish, even if that fish doesn't have either Finrot or Fungus. That said, some fish are more sensitive to medications than others, so when it comes to Stingrays, Puffers, Eels, and so on, holding fire until you're fairly sure there's a bacterial or fungal infection is definitely worthwhile.
Cheers, Neale.>

Columnaris treatment; no, I think you're dealing with Costia! 11/04/10
Hi Neale,
<Kara,>
I have been scrolling through pages and pages of previously submitted questions, and doing a lot of research and I was hoping you could assist me with a problem I'm having in my 5 foot (100 gallon) tank.
<I'll try.>
Tank is a low tech heavily planted tank, stocked with 10 Rummynose, 4 Sterbai Corys, 6 Kuhli loaches, 3 x true SAE's and 5 half grown angelfish. The tank is stable, with no water quality issues ever experienced, and has been set up for 6 months. It is well filtered with a large canister filter (2400lph), and the tank has good water flow/current. I have had the Rummynose for 4 months - when they arrived (mail order) they had ich, so these are survivors of that and have been super healthy and eating like pigs since. The Cory's and sterbais I've had for about 3 months, the 5 angels about 6 weeks. All went through a quarantine period in a bare, cycled tank. When I got the angels, one had a white pimple by his mouth, it never changed throughout quarantine, and seemed to fade, so I assumed it was just an innocent pimple. I recently went away for a week and left the house sitter to feed the fish. Everything was fine, water parameters excellent. I did notice that one Rummynose looked as though it might have had a slightly foggy eye, at the time I thought it was a trick of the light.
<Most often caused by physical damage if just one eye; if both eyes, environmental issues become more likely.>
When I got home, I discovered the majority of the Rummynose had pale patches on their backs around the dorsal fin, no evident signs of Finrot, but some had white patches on their eyes. After some research I found this to be a possible classic sign of the start of a Columnaris infection.
<Don't agree at all. Columnaris, also known as Mouth Fungus, is a fairly distinctive disease. As its name suggests, it's most often found around the mouth, and the lumps have a thready texture similar to that of fungus. It is usually some shade of grey though, so while similar looking to fungus, should be fairly easily distinguished from the white threads typical of fungus. Are you sure you are not confusing Columnaris with Costia? Costia, also known as Slime Disease, is a skin parasite that causes patches of grey on the body. It is readily treated if caught early.>
I immediately tested the water and found: Ammonia: 0 Nitrite: 0 Nitrate: 10 - this raised my eyebrows because I have NEVER had a nitrate reading in this tank due to the abundance of plants. I feel that to have suddenly had the level rise to 10 in spite of all the plants, there may have been an ammonia/nitrite spike preceding this possibly due to the house sitter overfeeding? - Hard to say anything factually as I wasn't here. The stress of an ammonia/nitrite spike could have triggered the start of the problems.
<10 mg/l isn't all that high, so if this is the worst your house sitter did, you were lucky. Generally, if you're gone for less than 10 days, skip feeding altogether; for longer periods, leave enough food in individual envelopes for one or two meals per week. Hide all the rest!>
PH - 8 (Usually sits at 7.8 - the addition of extra black gravel raised the ph a little more than I'd expected.) GH - 8 KH - 7 I also found the light had been left on 24/7 while I was away due to a timer malfunction - which may have further stressed the fish and certainly affected the plants.
<Possibly, but not seriously. I routinely do this when away on vacations, and the plants are fine. A bit overgrown sometimes, but nothing serious.>
I immediately did a 25% water change despite the ok readings, and fixed the light. Everything I read on Columnaris said that it thrives in hard, warm water, and can overcome fish when they are stressed, injured or subjected to unsuitable conditions. Treatment widely recommended was Tetracycline - which is basically ineffective with a PH as high as mine. The next recommendation was Oxytetracycline in their food - I was unable to acquire any despite talking to 3 different vets. While I was trying to get hold of treatment, I began dosing Pimafix on the advice of a vet, but I believe this was ineffective, so after 4 days I eventually got a bottle of Tri-Sulfa tablets, and after another water change began dosing at the recommended 1 tablet per 40 liters, which for my tank is about 9 tablets. My bottle says repeat in 3 days if necessary. So I did another water change, and dosed again on the 3rd day. Tomorrow they will be due for a 3rd dose if you think it wise to continue. I have found the saddleback lesions on the tetras to be not as grey/white as they were, it's fading back to normal colour, however 2 still have distinct white patches on their eyes. The kuhlis/Corys have never displayed symptoms and still look fine. One of the SAE's was pale, but now looks completely normal. The angels on the other hand are a different story. The pimple that had been on the one angel had flared up again and was a little woolly, it is no longer woolly, but it's still present despite treatment with tri-sulfa, and a few of the other angelfish have developed ragged fins with milky spots on the ends that do not seem to be improving ( 2 are particularly aggro with each other, so injuries to the fins may be allowing the bacteria to gain a hold). Should I continue treatment with the tri-sulfa? It says in severe cases that you can double the dose to 1 tablet per 20litres, however I'm not sure if my Corys, kuhlis and tetras will cope with the higher dose. Do I need to allow the tri-sulfa longer to take effect, or should I conclude that it is not working efficiently and try something else? Water parameters as at this morning are Amm/Nitrite 0, Nitrate less than 5ppm, PH steady at 7.9. So far I have not lost any fish, and all are still active and eating despite symptoms. However I am very eager to be rid of this once and for all and would like to know how much longer I should continue treating with the tri-sulfa. Any help you can give me would be much appreciated. Sorry for the long email. Regards, Kara
<Kara, the bottom line is I suspect you're treating for the wrong thing. Costia (strictly speaking, Ichthyobodo) symptoms include excess mucous production leading to grey patches, and in serious cases, bloody sores on the body. Affected fish often breathe heavily, become lethargic, and go off their food. Treatment typically involves the use of formalin-based medications, but these can be a bit hard on catfish and loaches, so use judiciously. Brackish water is very good for dealing with Costia, but obviously only suitable for those species tolerant of brackish conditions and periodic seawater dips, such as livebearers. Cheers, Neale.>

Poorly eel... Ps. Sorry for such a long email, but i thought I'd tell you as much as i could,,, also forgot to add, All the other fish seem ok... And the eel never seemed to eat anything... i got some maggots from the local fishing shop.. the other fish liked them, and the eel showed more interest in them than bloodworms, or anything else I'd been trying to feed him, and looked as if he was trying to eat one, he made a move towards it, but didn't get it in his mouth,,, so I'm not entirely convinced he's eaten too much since i got him.. (about 3 weeks ago) hope you can help.... Sami <This spiny eel is extremely mal-affected by a bacterial infection... though often termed fungal... A very quick administration of antibiotics to the system (Chloramphenicol if you can get it, Spectrogram (product) if not... at double dose... 250 mg. per five gallons, addition of a teaspoon of aquarium salt per five gallons... in a separate treatment system, attention to water quality while there... offering tubificid worms as food... Might save this specimen, but doubtful at this stage. Bob Fenner>

Septicemia Hello, First, I wanted to say that your website is much appreciated and very helpful. The problem I'm having is properly diagnosing and curing my female Bettas (both are opaque whites). One of them now looks like a butterfly Betta due to the red streaks on ALL fins...the other has a tiny red spot on her tail, and some red streaks on her anal and dorsal fins. Thinking they might have Septicemia, I've treated them with Maracyn 2 for 10 days and it doesn't seem like anything happened. I'm not sure if I should repeat treatment again with Maracyn 2...Any further suggestions or help on how to cure these red streaks are welcome. The following is more detailed information regarding their background, etc. Current symptoms: They still have their red streaks in their finnage. They've been off their meds for about 10 days now, and their attitudes have severely changed. They are lethargic and listless, tend not to eat as much, and scared (they often hide when I come to look at them or they dash quickly into their pagodas when I gently drop their food in)...They used to be more active swimming around (mainly because the smaller one would get chased every now and then) and friendly (coming to greet me when I'd feed them) Recent Changes & Food: 3 days ago, I put a clear divider to protect the smaller female (stop the chasing) since their behavior change. Sometimes, the sisters hang out facing each other through the divider...I can't tell if the smaller one now lost her appetite due to depression? She still eats, but very little (maybe 3 pellets and 2 live brine shrimp once a day). It's odd because the other female (the one that now looks like a butterfly) eats well. I usually feed them twice a day mixing flakes, pellets, and live brine shrimp. For example, 6 pellets & 5 brine shrimp for each Betta twice a day...Am I overfeeding? <Yep! Cut to all they eat in a minute or two once a day.> Tank situation: I have them in a 10-gal with a sponge filter (I will be getting a 2nd filter, now that the tank is divided). I do weekly water changes (50%) adding only aquarium salt (Hawaii's tap water doesn't have chlorine). I have enough floating water sprites (Ceratopteris) to cover about half the tank (I clean off dead leaves and rise plants weekly). For their "homes" they each have a ceramic pagoda... <Are you sure about the chlorine? You may have chloramines which must be removed.> Background: I got the pair in early April (fully white). I didn't change their water for about 3 weeks (since my aquarist friend told me not to) until one female showed some red streaks in her fins. However, I was told that they were just stressed out and no treatment was necessary. I then began to do water changes weekly...When the red streaks worsened and also began to appear on the other female in early May, I began to worry. That's when I started treatment w/ Maracyn 2. Thanks, Nell <Sure sounds like a bad case of Septicemia. Many times this can be cured with water changes alone. Lots of them. Like 50% daily using a gravel vac to get all the old organics out of the system. I do not see any mention of water tests. You should be testing for ammonia, nitrite and nitrate. You are looking for zero on the first two, nitrates below 20ppm. With the signs you are seeing I would bet you have very high nitrates. The water changes will correct. If they continue to decline treat with Oxytetracycline. If possible remove them to a QT tank for treatment. The meds will kill off your beneficial bacteria causing

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