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FAQs on Freshwater Infectious (bacterial, fungal) Diseases: Bacterial

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, Causes/Etiology/Prevention, Cures/Medications, Case Histories: True Fungal, & By Type/Organisms: Fin & Mouth Rot, Columnaris, Mycobacteria/Tuberculosis, Whirling Disease, Bettas w/ Infections,

Bacterial infections can appear as white or grey slimes, reddening, bumps... or no physical symptoms at all. Can be blood-borne, enteric...

Columnaris Denisonii Barb/Redwag Platy        9/30/16
I noticed one of my denisonii barbs, and Redwag Platy had lesions, which I assumed was columnaris.
<Mmm; maybe.... what re cause here? Such infections don't occur w/o environmental prompting>
I did a lot of research and the common theme, I found, in treatment for columnaris was reducing temperature, salt, KanaPlex, MetroPlex, and furan2.
I moved the barb and platy from my 75g to my 10g hospital tank, and began medicating the water with furan2, salt, and feeding KanaPlex/MetroPlex.
The platys dent/lesion has lost the white line in the dent, and seems to be doing fine. My barb, on the other hand, developed even more lesions, but is very active and eating well.
For the second round of medications, I medicated the water with furan2, salt, KanaPlex/MetroPlex (I did not dose food).
I repeated the first round of medication, making it 3 total rounds of medication.
My barb has not developed any new lesions for about 5 days, and my platy looks normal. My question is when do I know my barb and platy are healthy enough to go back into my main tank?
<I'd wait a good few weeks beyond when these "lesions" are gone>
I've had them in my hospital tank for 3 weeks, and I feel the barb (4.5inches) is getting a bit stressed in the 10gal, and without his school.
Thank you!
<Keep changing some (a few gallons) of water daily... From their main/display system. Bob Fenner>

Columnaris Denisonii Barb/Redwag Platy     /Neale       10/1/16
I noticed one of my denisonii barbs, and Redwag Platy had lesions, which I assumed was columnaris. I did a lot of research and the common theme, I found, in treatment for columnaris was reducing temperature, salt, KanaPlex, MetroPlex, and furan2.
I moved the barb and platy from my 75g to my 10g hospital tank, and began medicating the water with furan2, salt, and feeding KanaPlex/MetroPlex. The platys dent/lesion has lost the white line in the dent, and seems to be doing fine. My barb, on the other hand, developed even more lesions, but is very active and eating well.
For the second round of medications, I medicated the water with furan2, salt, KanaPlex/MetroPlex (I did not dose food).
I repeated the first round of medication, making it 3 total rounds of medication.
My barb has not developed any new lesions for about 5 days, and my platy looks normal. My question is when do I know my barb and platy are healthy enough to go back into my main tank?
I've had them in my hospital tank for 3 weeks, and I feel the barb (4.5inches) is getting a bit stressed in the 10gal, and without his school.
Thank you!
<Bob Fenner has covered the essentials here. But a couple extra comments if I may... For a start, do understand this species subtropical. At tropical temperatures it isn't entirely happy, and in particular low oxygen levels and high nitrate levels will stress them. If the tankmates are Platies, which are perfectly happy in cooler conditions, I'd be keeping this/these species around 22-24C/72-75F rather than anything warmer. Optimal conditions for Denison Barbs is likely a few degrees cooler than this. Let me have you read the Fishbase page on this species, here...
Certainly optimise water circulation and oxygenation, though I will state that Platies are still-water fish, and will not thrive in the brisk currents Denison Barbs need (though Swordtails, being stream-dwellers, would actually be pretty decent companions). Secondly, I'm not sure adding salt is terribly helpful. Barbs vary in their tolerance for salt, some actually inhabiting low-end brackish habitats, but these barbs are definitely inland fish, and I can't see any advantage to even trace
additions to salt unless you're dealing with something specific where salt is the cure (like Whitespot). Instead, I'd be coupling a general purpose antibiotic alongside an aggressive approach to optimising water conditions.
Denison Barbs have, overall, a poor to middling track record in captivity; relatively few reach their proper size and live anything close to a full lifespan. Read, review, and act accordingly. Cheers, Neale.>
re: Columnaris Denisonii Barb/Redwag Platy      10/1/16

Thank you for the quick answers!
I am going to remove the platys (3) and move them to my 20g long because there is substantial water movement with an AquaClear 110, 520gph canister filter, and an 325gph hydroponic air pump.
<Sounds wise.>
The issue might have been temperature (I do two 50% water changes a week on the 75g), as summer just ended here and my tank has been at a constant 80F for 3 months.
Should I look into re-homing the barbs if I cannot consistently maintain a lower temperature throughout the entire year?
<Nope. Summertime highs are fine. The issue is year-round high temperatures. Basically, the ideal approach would be to allow the tank to warm up in summer, but during the winter make sure it cools down a bit, so there's some seasonality. This will be much closer to "the wild" and ensure your Denison Barbs stay healthy. Lows of 15 C/59 F are probably not
necessary, but something like 20-22 C/68-72 F would be beneficial, and still allow a wide variety of tankmates. Many barbs, danios and minnows, many loaches, numerous Loricariids, most Corydoras, and a few cichlids (like Acaras) and livebearers (such as Swordtails and virtually all Goodeids) prefer precisely these conditions. Bronze Corydoras and
Bristlenose Plecs are two examples of widely sold and inexpensive fish that would thrive in a riverine tank adapted to Denison Barbs.>
Thanks again!
<Cheers, Neale.>

African Dwarf Frogs and Internal Bacteria Fish treatment.    11/4/12
firstly thank goodness for your amazing site - it's always there for any fishy questions and always helps me out!
<It is definitely a hidden gem.>
My tank contains 6 Platys 2 Angel fish 3 gold mountain minnows, 1 bristle nose Plec, 1 Plec, 3 clown loaches, 6 ADFs, and, as of today one lonely Leopard Danio.
<How big of a tank are we talking about here? Also, the mountain minnows are not a good mix with these others because they are cold water fish, not tropical fish.>
I had two dannys, but I found the female dead this morning - She had a lot of eggs in her. I have noticed that the four female platys I have are very bloated, I think it is because they have a lot of eggs also.
<Not likely. Platies are livebearers.>
The two males are very slim and healthy looking as are the clown loaches. I am concerned that perhaps there is a bacterial infection causing the female fish to look so bloated as well as them having eggs.
<The females are probably gravid, i.e., pregnant. This is not caused by male platies, not bacterial :).>
I am worried this caused the Danny to die.
<Hard to say. You will get occasional fish who succumb to disease in an otherwise healthy tank. The disease vectors are always there in the tank., it's just that healthy immune systems fight them off. Were the scales of the Danio pineconed when it died?>>
I have also noticed that some of the minnows have some dark patches over (possibly between?) their scales that they did not have before.
<Could be any number of things. Fish can and do change color depending on their surroundings, stress level, moods.>
The water parameters are good,
the tank has a filter, bubbler and heater that is set to 24.5 deg C. Do you think it could be a bacterial infection?
<Not without more compelling evidence, no.>
If so, do you think my 'interpret anti internal bacteria treatment' would be safe to use with the frogs? There are no indications on the packet or on their website either way
<Try a Google search with "African dwarf frogs antibacterial medication." I get lots of hits. Or, read Neale's article here:
http://www.wetwebmedia.com/fwsubwebindex/FrogsArtNeale.htm  >
- though it does say on the side of the packet 'not for fish intended for human consumption' I do not think they realised they have it the wrong way round ha.
<No, they mean don't use on fish people will eat. No comma between "fish" and "intended.">>
The product contains Bronopol, Formaldehyde and Benzalkonium. Unfortunately I do not have the capacity to quarantine the frogs away from the fish at the moment as I already have an 80L tank and another 40L tank for my axolotl in my room. Perhaps I will have to find a way of doing this. I read on website that the frogs 'breathe through their skin' Is this true?
<They come to the surface and take a breath, then hold it for an incredibly long time.? Keep an eye on things and if you notice any new to indicate bacterial infection, let us know. I mean symptoms like red patches or Finrot.>
I hope to hear from you soon.
Re: African Dwarf Frogs and Internal Bacteria Fish treatment    11/7/12

Hi rick
I am aware Platys are livebearers so perhaps I should have said pregnant instead of eggs hah,
I also didn't think to read that sentence without the comma (I am a very poor English student!)
<Ah yes.>
The tank is 85L  <22 Gal>. the frogs seem to be healthy, there are no unusual discolourations they all eat happily, and seem to come up as often as they always have done for breath.
When I was sold the mountain minnows I was told they were tropical, I'm very disappointed to find out they're not :(  The Danny wasn't pineconed. When I found her she had a small gap in her tummy (where her eggs were) and a small part of her tail fin missing. I think someone in the tank had had a little nibble at her tail after she had died,
<No dropsy then, so still no real clue as to what happened. Once a fish is dead, if it is not removed immediately it will be eaten by other residents starting with the soft parts.>
I am not sure if the gap in her tummy was the same or if it was caused by bloat or something?
<I'm not sure what you mean by gap. Was it damaged, as if it were eaten? If so, then it probably happened after death.>
I saw her in the morning and there was no sign of her looking bloated or unwell. Do you think she could have been stressed as she was the only female in with one male?
<Maybe. I've had female Endlers leave a tank to escape male harassment.
Platies are from the same genus (Poecilia) so it's possible.>
The parameters are 0 nitrates, ammonia is the lowest on my colour scale in the 'safe' section. Chlorines are in safe also. Ph is mid range in my safe scale which, I believe is around 7.5. It has remained constant and not caused me any problems so far. Thank you so much. I am afraid I am a complete hypochondriac when it comes to my fish.
<Nothing shouts problem to me. Without other evidence to the contrary, my guess is that this death was an isolated event. You may never know the root cause. Unless you see some additional signs of trouble with the fish and frogs that are still alive, I think the best action is to carry on normally and a keep sharp eye for problems with the other fish.. - Rick>
Re: African Dwarf Frogs and Internal Bacteria Fish treatment    11/7/12
Thanks Rick. I told you I am a hypochondriac when it comes to my fish! Many thanks again
<You are very welcome. Good luck with them. - Rick>

Sick Molly?  10/25/11
Sick Molly? (RMF, anything to add/refute?)<<Nope>>

Hi WWM Crew,
I'm new to the hobby, and at a complete loss. I've Googled as much as humanly possible, but lacking the proper terminology can make things tricky. I believe my Molly may be sick -- perhaps constipation, dropsy or a tumor?
First, I'll start with the (hopefully) relevant parameters:
Aquarium: 29 Gallons
Filter: Rena Filstar XP3 w/ 2L Ehfisubstrat Pro
PH: ~8.0
Ammonia[*]: <0.25 ppm
Nitrite: 0 ppm
Nitrate: <5 ppm
Temp: 27 C
Salinity: ~1.004 sg
<Sounds a good aquarium for Mollies. While ammonia is toxic, even at slight concentrations, Mollies don't seem particularly sensitive to ammonia when maintained in brackish or marine conditions, hence their (largely historic) usage in maturing new marine tanks before true marine species are added.>
[*] We triggered what I believe to be a mini-cycle last weekend when we added three new tankmates to the aquarium. Previously, the tank was fishless cycled using bottled ammonia (4 ppm per day) until the ammonia and nitrite levels dropped to zero and nitrates were present. We then completed a ~75% water change to lower the nitrates. The first three fish were then added, and I checked the parameters daily. Now that we experience nonzero ammonia, we change about 25-40% of the water daily until the ammonia drops below 0.25 ppm, with one exception: an Ick treatment** (the new tankmates came with friends!) where I could only change the water every other day. During this, I dosed the tank daily with Prime to detoxify any ammonia.
** API Super Ick Cure Liquid
Presently, there are six Mollies inhabiting the tank. Only one shows signs of this sickness so far. The first thing we tried was to administer the correct dosage of ParaGuard -- which, according to the info, appeared to be a cure-all for the inexperienced like us (antibacterial, anti-parasite, fungicide, etc.). It did not appear to help.
<Indeed. While Paraguard is a good medication, it won't cure everything, and is primarily useful for treating external bacteria, parasites and fungi. It will be of little to no value when treating internal ("systemic") infections. There are essentially two sorts of medicines in the world.
Those that kill pathogens on the outside of the fish, and so work best added to the water *and* dosed to the size of the aquarium; and those that kill pathogens inside the fish, and these work best when administered via food or injections *and* dosed for the size (weight) of the fish. There's little overlap between the two, and on the whole, aquarists can expect good results from the external medicines because dosing to the size of the tank is easy. Medicines that treat internal infections are much, MUCH less reliable because aquarists can't judge the right dose, and a one-size-fits-all approach simply doesn't work. When fish are sick with something systemic, it really makes a HUGE difference getting a vet
involved because a vet can judge the right amount of medicine for the size of the fish, and if necessary, inject that dose into the fish. The worst situation is treating an internal infection with a medicine that is dosed by the size of the tank -- this is unlikely to be the right dose for a fish of given size -- imagine an Oscar and a Neon both in 50 gallon hospital tanks -- which would need more medicine?>
The Molly in question has a bulge behind her right gill, which is increasing in size. Her scales in this area are also beginning to protrude. Thinking it was constipation, we have been feeding the fish peas and spinach for the past two days (they generally get spirulina wafers twice daily*, and livebearer flakes once daily** with random greenery substitutions throughout the week). This Molly maintains her appetite, and
does poop, if not as much as some of her tankmates.
* Nutrafin Max Spirulina Meal Tablets
** Nutrafin Max Livebearer Flakes + Freeze Dried Tubifex Worms However, during non-feeding time, she is somewhat active, but appears to "gulp" constantly as if she was trying to eat or breathe and generally hangs out near the middle-to-bottom of the tank. The gulping is really nonstop.
Sometimes, she swims almost 90 degrees vertical, triggered when the other fish pass by.
Thank you for your help!
PS: Pictures attached. Sorry for the quality, they tend to be fast little buggers! :)
<Mollies are of variable quality these days, and systemic infections that cause bloating and dropsy are common. Maintaining them properly helps prevent problems, but once the bacteria or Protozoans multiply sufficiently to cause severe stress, like this poor chap, then there's little you can.
One possibility is Camallanus worms, these are common among livebearers.
But they're distinctive in revealing themselves as little red threads at the anus; have you seen any of these? Shimmies is another common problem, and apparently neurological. It tends to be untreatable directly, but goes away when Mollies are moved into the right environmental conditions. My gut feeling here is that this Molly has something like a Mycobacteria infection, and even with veterinarian help, it would be unlikely to recover. I've seen this from time to time with livebearers, including my own, and tends to happen when fish are past middle age and, crucially, I haven't given them the very best care, so the tank is overstocked, oxygenation is a bit low, the water hasn't been changed much, or summertime temperatures have been excessively high. Euthanasia is usually the best step forward.
Cheers, Neale.>

Re: Sick Molly? (RMF, anything to add/refute?) <<Nothing>>   10/27/11
Hi Neale,
Thanks so much for the prompt and informative reply.
<Glad to help.>
I took the sick molly to a vet after work today, and he confirmed your suspicions -- Mycobacteria -- and euthanized the fish for us.
<Too bad. Sadly not uncommon with this species, and livebearers in general (esp. Platies and Guppies).>
I wish we could have done more, but I think it was the humane choice?
<No question at all. With fish, there's often a very narrow period of time during which you can treat successfully, especially with small fish. Often a few days. If you miss that window of opportunity, your best bet is often to euthanise the fish, then go back to the aquarium and see what the problem might have been. Fix them, then let the tank settle for at least 4 weeks before you add any more fish.>
We had purchased this particular fish three days ago, so it was suggested that it was probably ill before we even got it home.
<Oh, I agree. Mycobacteria infections take longer than 3 days to get to this point. They likely incubate for a few weeks before overwhelming the fish's immune system.>
I realize that you are likely busy with other aquatic crises, but if you have the time, could you verify that we are raising them in as close-to-ideal conditions as possible?
<Are you talking about Mollies? The key things are water chemistry and water quality. Water chemistry needs to be hard and alkaline, the harder the better. If you're just keeping Mollies -- the ideal situation -- then try using the Rift Valley salt mix described in the article below. Even at half the dose, you should find life a lot easier.
At full dose, you will have to limit tankmates to hard water species, so you might decide to go with brackish conditions instead, adding anything between 6-9 grammes of marine salt mix per litre, the lower end if you have live plants. In such conditions you can add brackish tankmates such as Knight Gobies or Violet Gobies. Next up, water quality. Ammonia and nitrite must be zero, and nitrate as close to zero as possible, less than 20 mg/l certainly. In brackish water, the presence of salt actually makes nitrite and nitrate less toxic, so this issue isn't quite so critical. In short, your aquarium seems about right to me, and if your Mollies are otherwise healthy, I'd put this death down to bad luck. Wait, see what happens, and don't add anything else for a month.>
Being newbies, we purchased and configured everything as described on WWM; the "truth about mollies" article you wrote was particularly informative!
Truly appreciated,
<Mollies are lovely fish, and once established, easily justify the extra care they need. Do keep your eyes peeled for Giant Sailfin Mollies. The males comfortably fill a man's hand, and the females can reach 15 cm/6 inches! There's also Liberty Mollies, some of the prettiest fish in the hobby, and actually quite hardy, but sadly also rather nippy, so best kept as a single-species set-up. Cheers, Neale.>

Columnaris treatment; no, I think you're dealing with Costia! 11/04/10
Hi Neale,
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.>

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.>

Establishing an optimum bacterial population 4/17/09
Dear Crew
I have a question about establishing a bacterial culture in an aquarium.
<Not an issue; the bacterial population will expand and contract to the biomass of fish in the tank. The only limiting factors are oxygen availability and physical space, the two issues that determine whether a filter is adequate for the task. More flow = more oxygen, and more media = more physical space.>
Long, long ago (in the 1970s) I was taught that an aquarium performs best if it goes through a crisis, in the sense that it undergoes a large bioload early in its life.
<Yes and no; the filter bacteria population grows precisely at the rate determined by the oxygen availability, the physical space for them to inhabit, the availability of ammonia/nitrite, the temperature, and the pH. If you have a lot of ammonia early on, yes, the bacterial population can grow rapidly compared to an otherwise identical tank with less ammonia. But unless that high ammonia concentration is maintained, the population will quickly die back to a small population maintained with less ammonia. They don't "hibernate" in any meaningful sense waiting for ammonia spikes weeks or months apart. Hence, you need to cycle a filter with an ammonia source equivalent to the biomass of the fish being added, and when you do add further fish on top of that amount, you add them in small, spaced apart batches so the bacteria population can multiply upwards.>
To achieve this, when setting up a new aquarium I would get the filters running, add some bacteria (usually sand from an established tank), and throw in a few dead shrimps or a piece of fish fillet.
<As good a way as any.>
There would be no inhabitants in the tank except the bacteria. Over the ensuing weeks, the meat would rot, the tank would stink, and when the cycling process was finished, Id do a large water change.
The thinking behind this was that if you caused a crisis like this, with a massive ammonia spike early in the piece, you would establish colonies of bacteria in the filtering system that were at the maximum potential that could be achieved.
<Sort of; what you're doing is creating a source of ammonia equivalent to however much food you'd add if there was a fish in that tank. It doesn't matter to the bacteria whether the ammonia comes directly from a shrimp rotting on the sand or else a shrimp that passed through the gut of a fish. Ammonia is ammonia is ammonia. But, here's the thing: the art is in waiting for the ammonia to drop to a safe level, and then adding a fish or two to keep "topping up" that ammonia for those bacteria in the filter. Consider an extreme example: say you waited three months. The ammonia produced by the shrimp will have been all used up by then, and the bacteria in the filter would have died back to some minimal value. Likely not zero, because there'd be algae and other micro-organisms in the aquarium, so there'd be some small amount of ammonia, but nothing like as much as if there'd been a school of Guppies.>
The idea was that this optimum population of bacteria would occupy all the available sites in the system, and they would work at nitrification as need arose.
<There's no "optimum" level you can build into a system; the bacteria numbers will be limited by whatever is in least supply. This is called the Law of Limiting Factors and affects numerous biological systems. If ammonia is at a low level because a fish tank is empty, it doesn't matter how big the filter is, or how optimal the pH, or how perfect the temperature -- the bacteria population will be small.>
In other words, if you had a small bioload in the tank, the bacteria numbers would remain constant but they would have to work less.
<No. Allowing for a certain lag for the bacteria to die back, the population would be exactly proportional to whatever is in least supply.>
If you gradually increased the bioload to the maximum appropriate for the size of the tank, the bacteria would adjust their metabolism and work harder to cause nitrification. It was thought that the population of bacteria would remain constant, with fluctuations in activity depending on the bioload.
<Not sure they adjust their metabolism; rather, you have X bacteria, or 10X, or a 100X bacteria, depending on how much of whatever limiting factor is available.>
The concurrent idea was that if you didnt cause a big crisis, but cycled the tank by only placing in it a few hardy fish, the bacterial population would establish only to meet that bioload, and the colonies in the filters would not be as dense as it would have been if youd gone the full crisis way.
<Yes, when you cycle with, say, 4 Guppies, you get sufficient bacteria in the filter to consume the ammonia produced by 4 Guppies; no more and no less.>
In other words, there would be less bacteria by using the slow method.
<No, you get precisely the same. All depends on the limiting factor.>
It was thought that this would constitute the bacterial population for the life of the aquarium and that the numbers of bacteria would not increase when you increased the bioload the bacteria would simply work harder to handle nitrification, and the system would never be as capable of handling a large bioload or a crisis in the way that a full crisis system would..
<No; what limits the bacteria population isn't how you created the tank, but what the conditions are at the moment. Double the amount of ammonia in any aquarium and the bacterial population will (within a certain period of time) double as well (assuming other factors, such as oxygen or physical space, aren't limiting).
Therefore, it was taken for granted that, if you wanted an aquarium to have its full potential for nitrification, the full crisis method was the way to go.
Now, this may be old thinking, and Id be glad if you would comment on what current thinking is. Im setting up a large freshwater system that will eventually be heavily stocked, and Im debating whether to go with the slow method with a few fish or to use the fishless ammonia method to cause an initial spike in the hope that it will give me better long-term results. Is there an advantage of one method over the other?
<Absolutely no advantage to creating a "crisis" if you don't follow it up with an equal amount of ammonia day-in, day-out. If you add some shrimp and the ammonia concentration goes to, let's say, 10 mg/l, but then two weeks later has dropped to 1 mg/l, then the number of filter bacteria in that aquarium will be precisely the same as an aquarium given 1 mg/l every single day. Biological systems are ALWAYS limited by whatever is in least supply at the time, and NEVER expand to the potential of what might have been there in the past or might happen again in the future.>
Im sorry this is so wordy.
Les (Australia)
<Hope this helps, Neale.>

Re: Establishing an optimum bacterial population  4/18/09
Neale, that helps more than you can imagine. Many thanks for this most comprehensive collection of information. That has settled years of wondering for me. At last I can approach what I'm doing in an informed way.
Best regards to you.
<G'day Les. Happy to have helped. Good luck cycling your new tanks, however you choose to do it! Cheers, Neale.>

BW Tank? 6/5/04 <Hi Eric, Pufferpunk here. Sorry I took so long to get back to you.> Please, help me determine a possible cause of illness in my Sailfin mollies. I have a 55 gallon tank that is brackish. The contents of the tank are 2 Gourami, 2 red-eye tetra, 4 black Neons, 3 black-skirt tetra, 3 lemon tetra, 2 adult red velvet platies, 1 plecostomus, 1 rainbow shark, 4 adult silver mollies, 1 adult Dalmatian molly (lyre-tail) and approx. 15 molly fry.  <Oh my goodness! The only fish in your tank that would appreciate any salt, will be the mollies. All your other fish come from soft water, which is the opposite of BW. How much salt is in there? Just adding some salt to your tank, does not make it a brackish tank. Read about BW here: http://www.aquarticles.com/articles/management/Pearce_Brackish.2.html  & http://badmanstropicalfish.com/brackish/brackish.html .> All parameters of the tank are stable, all other fish are healthy....except the adult Dalmatian molly. I have had a total of 4 (including this one) Dalmatian mollies in the past 6 months and at least 2 of them have suffered similar fates. It starts with patchy loss of scales/color and progresses to weight loss until their ultimate demise. They still eat and swim normally. The first one that developed this illness had me so concerned about cross-contamination and looked so pitiful, that I euthanized him. The first time I've had to do that! Then the other adult Dalmatian started developing the same symptoms. None of the other fish in the tank show any signs of illness, and are breeding well. I'm concerned about fish T.B. That is why I didn't want the first sick fish to die in the tank. I read the other fish ingesting the dead sick fish is sometimes the way it is transmitted. This is a very slowly progressing process. It takes weeks or months before they reach the full extent of the illness. What is the lifespan of a molly? Could these fish just be old? Why don't any of the other fish display symptoms of illness? I have treated the tank in the past with antibiotics, Methylene blue or malachite green, and MelaFix. I can't figure out if it is a parasite or other disease, why it takes so long for it to affect the fish and why other fish aren't simultaneously ill. What should I do?  <This does not resemble the symptoms of TB. Generally, with TB their spine would be bent. It could be a bacterial infection. The stock you have, may have a congenital problem with their immune systems if none of your other mollies are getting it. As far as eating normally & loosing weight, this is a symptom of internal parasites, which isn't very common in tank-bred fish. You can read up on diseases here: http://www.fishdoc.co.uk/disease/clinicalsigns.htm  & http://www.fishyfarmacy.com/ . Always quarantine your sick fish, so you don't have to treat the whole tank, disturbing the biological filtration in the main tank. Also, this prevents spreading diseases further to the rest of the tank. You need to consider if you want BW fish or FW fish & only keep one kind. Keeping either in less than optimum conditions, can compromise their immune systems. ~PP>> 

Cichlids Melting   2/6/06 I am writing to you because I have found nothing on a disease called cichlid melt. < First I have heard of it and I have been keeping cichlids for 38 years.> My young Oscar died.  I brought the body to the pet store to see if they could make sense of the Oscar's skin condition.  Both sides looked eaten away.  They told me it's cichlid melt and compared it to leprosy.  They said it's highly contagious and there is no cure.  They told me to take down my entire tank and wash everything with bleach.  I have a 72 gallon tank, so I'm hoping I don't have to get that aggressive.  I presently have 3 parrot fish who seem to be OK, as well as one pearl cichlid.  I have lost about 5 other fish within the past couple of weeks.  None of them seemed to have what the Oscar did, however, two of the cichlid's had puffy and deteriorating scales protruding out of its head.  I've had fish for years and never experienced such a thing. Any ideas or suggestions?  Have you heard of Cichlid melt? Thank you Shannon < You have a bacterial infection that is eating the skin of your fish. Do a 50% water change, vacuum the gravel and clean the filter. Check the nitrate levels. They should always be under 25 ppm. Treat with Nitrofuranace as per the directions on the package.  After treatment, you will need to add a high quality carbon to remove the medication. When the water is clear add Bio-Spira to replace the good bacteria needed for biological filtration. Then feed your fish once each day and only enough food so that all of it is gone in two minutes.-Chuck>

Cichlids With Bacterial Infection  - 2/4/2006 My son brought home a blue cichlid, an Oscar, and one of those fungus eaters. (looks like a little shark, but i don't know what is called). I have a 39 gal. tank filled with fresh water, which I change weekly, two filters and an  air pump. I never heard anything about water chemicals until now. I feed them floating pellets two or three times a day. I don't know much about fish, but I have noticed the blue cichlid is growing orange wart like growths on the sides at the root of the fins.  It started showing about two or three months ago.  I didn't pay much attention in the beginning because I thought the fish was simply growing in size and that was part of it. they have grown a lot since we got them.  the Oscar is about 12 in, the cichlid is about 7 in and the other one is about 10 in), but the last few weeks, I noticed that one side is bulging out while the other seems to be "falling off in tiny chunks".  That's the best way I can describe it. What can I do? < Do a 50% water change, vacuum the gravel and clean the filter. Treat with Nitrofuranace as per the directions on the package. Fed once a  day and only enough food so that all of it is gone in two minutes. High nitrates contribute to bacterial infections such as these.-Chuck>

Oscars With Bacterial Diseases  - 2/4/2006 Hello, Can you please help me? We bought 2 Red Tiger Oscars about 5 months ago and have already lost 1 to this disease already. It started with these small indentations in their skin which have now got larger on the remaining one. Also the remaining Oscar also has a whole in his top fin which is slowly getting bigger and I think this will soon divide his fin into 2. We do a water change every 2-3 weeks. We were given a treatment called 'Melafix' which were told would get rid of it and if that didn't nothing would. We followed the instructions, took the carbon filter out, but nothing worked and this is how we lost our first through the treatment. Our local fish shop said to take a water sample in (which we haven't done yet) to see if there was a high level of acid in the water, but only the Oscars had this disease. We have different types of Parrot Cichlids but these are all fine If you could reply to my email that would be great, Thanks Rebecca < This is a bacterial infection brought on with water high in nitrates. Do a 50% water change, vacuum the gravel and clean the filter. Treat with Nitrofuranace as per the directions on the package. Feed once a day and only enough food so that all of it is gone in two minutes. Check the nitrates weekly. They should not exceed 25 ppm. Reduce them with water changes.-Chuck> Red Devil Cichlid With Internal Infection  1/2/07 Hello I have a Red devil cichlid that I got that has swim bladder for the purpose of trying to save him. The pet store gave him to me free because someone brought him in. He is a nice looking fish and is about 6inches and I have put him in a hospital tank and then added Epson salt raised the temp to 84F and treating the water with poly guard as well as trying to feed the fish with Metronidazole and garlic guard mixed in with some food as well as some green peas and doing daily 20% water changes and carefully replacing  the salt and poly guard. But the problem is that the fish stays on the bottom of the tank and cannot swim but only scoot's around on the bottom of the tank on his belly. He sometimes will go over to the food that I place in the tank but can't get the food in his mouth because he can't seem to raise up to pick the food up from the bottom of the tank. He often lays on his side until he see's me in the room then he sits back up on his belly. I noticed as well that yesterday and today that there was some blood in his stool. I have been treating him for about three day's now. Do you know anything else that I can do to get this fish better and how long do you think it will take before he gets better? Thank you for any help. <Remove any sand or gravel that can be abrasive to the skin of the fish. The infection has affected the swim bladder. Even if you cure the disease the swim bladder may not recover and become functional again. I would add Nitrofuranace to the mix and continue to treat for another week. These medications are not cheap. You probably could have purchased a healthy red devil for the money you will spend trying to save this one.-Chuck>
Panda Cory with Milky Film 10/13/05 Hello, <Good morning. Sabrina with you.> This is my first fish tank and your website has been tremendously valuable. I keep making mistakes, though, and lost 4 panda Corys. Just when I think I've figured out what I'm doing wrong, another panda gets sick. <Yikes. Starting out, most folks make mistakes, so do not beat yourself up on this. It is how we are prompted to learn.> I now have two pandas. One seems healthy and active, but the other has milky white clumps on one side of his body. They started about 2 weeks ago and are spreading. I'm attaching two photos...I hope you can open them. I don't know if it's a fungus or bacterial infection. <A tough question. I, personally, think this is Columnaris or some other (severe) bacterial infection. Good photo, BTW.> I've been treating the tank with Maracyn for 8 days now. Initially, there was a small red spot in the white patch that's gone now. The Cory hides but eats actively (sinking wafers and shrimp pellets) and his breathing seems normal. Both seem to tolerate the Maracyn. <I don't think Maracyn (Erythromycin) will treat Columnaris; even if this is something else bacterial, I doubt that Erythromycin is the way to go; it only treats gram-positive bacteria (that's bacteria that have a cell wall); there are few gram-positive bacteria responsible for illness in fish.> <<This is incorrect: The difference between "gram positive" bacteria and "gram negative" bacteria has to do with how they take up (or don't) a type of violet stain (re: peptidoglycan w/in cell walls) .  Try Googling, or view here  Marina>>

My tank and mistakes: -- 7 gal, power filter with venturi tube, sponge filter, heater, light, live plants, driftwood. -- 1 male Betta, 2 panda Corys (at most 4). -- temp 80F, ph 7.0, total ammonia < 0.1ppm (was zero before Maracyn), nitrites 0ppm, nitrates 5ppm, dGH 2, dKH 2. -- 30-40% water change and gravel vac every other day, Amquel, Nutrafin Cycle every other change. Temp change 1-2 degrees after change. <This is too much maintenance, once the tank's cycled.> -- mistakes: --didn't cycle properly and overfed; lost 2 Corys due to high ammonia. --problems keeping temp and pH stable; okay now. --initially fed Betta live tube worms <Tubifex worms, perhaps? Try to avoid these; blackworms are safer (as in, less prone to passing along disease to your fish).> and now some are living in the gravel. I vacuum but can't seem to get rid of them. Maybe the substrate wasn't clean enough. <This is okay. The worms in the substrate aren't of significant concern unless they are very numerous.> --Two other Corys gradually got sick. <Ammonia again? Or this illness?> --one died after one dose of Maroxy; did quick water change and stopped. --another died after one dose of Maracyn II, same. I feel terrible about losing these fish. Is there anything I can do if the Maracyn doesn't work? <I've shown this to Bob, as well.... his recommendation is to treat with aquarium salt and a furan compound.... might read here for more: http://www.wetwebmedia.com/furancpdfaqs.htm .> I don't want to add another chemical or medicine that might do more harm than good. <The Maracyn likely will not be of help here.> I won't add new fish. Through all this, my Betta has been very active, eating heartily, and seemingly oblivious. <I would remove him from this system immediately, lest he contract the illness as well. Normally I would recommend the opposite, removing the infected fish to a separate quarantine/hospital system, but I would be fearful for the Betta right now.> Thanks for your expertise! --Anita <Wishing you the best, -Sabrina>

Bubble Eye Goldfish - Bacterial Infection 7/11/03 I need some help immediately. My goldfish, a bubble eye, appears to have an infection with its bubble. One of the bubble seems to be congested with orange stuff. Please help me identify this disease and guide me on what to do. My other bubble eye have already died due to the same illness. Thank you. <if it is a pathological concern, it will almost certainly be bacterial in nature. Use a Furazolidone and Nitrofurazone (mixed) based medication like Jungle brand "Fungus Eliminator" (ignore the name). It would also be best to treat it as with all fishes, in a proper and separate bare-bottomed hospital tank. Best regards, Anthony>

Bacterial Hemorrhagic Septicemia I have a small orange goldfish that I moved to a 44 gal. tank about a week ago, along with a small comet. I had just set up this tank, which only contained two platys and an algae eater. I've had both of the goldfish for several months, and they have been very healthy. The orange goldfish still seems to be healthy, except for the fact that one side of his mouth is turning inward. I can see no sign of mouth fungus or fin rot or anything that looks abnormal. He is eating and using the bathroom fine and has plenty of energy. Before I moved him and the comet, I had them in a 10 gal. with two small Orandas that I had bought a few weeks ago. The Orandas had damaged fins when I bought them, but they were fine for about a week and I thought they were going to be ok. Then they started to develop red around the bases of their fins and red streaks under their chins, so I moved the two other goldfish to the new tank and treated the Orandas (which didn't survive) with fungus clear. I don't think the water in my tank caused the infection, because the two other goldfish had been living in it for months, and it had clean water and more than adequate filtration. The orange goldfish and comet have been doing great in the new tank for the past week, except that this morning I noticed that the orange fish's mouth is turning inward. Is that a sign of fungus, or could it have been damaged another way? Jacquelyn <The red streaks mean your fish are affected by bacterial hemorrhagic septicemia. Treat with Oxytetracycline. Usually caused by poor water conditions such as high nitrates. My guess is that we have the same underlying agent causing the mouth problem. The antibiotic should help both. I suggest you treat in a small tank as the meds will nuke the bio filtration in your main. Don>

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>

Bacterial Hemorrhagic Septicemia Hi guys, I just have a quick question, and was wondering if you could help me out? I noticed today that my Siamese algae eater has developed some red, vein-like structures around the base of its head and on its neck. They are not particularly large, but they are noticeable if you are looking at him. Aside from this, his behavior has been normal and he seems to be eating fine, and in good health. So, do you have any idea what these vein-like things might be? Thanks for answering my question, Mark <Hi Mark. Your SAE has bacterial hemorrhagic septicemia. Sounds bad, doesn't it? It's not. It's usually caused by high levels of organic material in the water. Do a few daily water changes and it should clear up on it's own. Then increase your regular water change schedule to keep things pristine. Don>

Re: best thing to use for bacterial pop-eye? Hi guys, One of my big rainbows has pop-eye....again. What's the best anti-bacterial medication to use for this?? Thanks, Ananda <a broad-spectrum antibiotic in QT is the best bet, but if it happened recently and is simply swollen (may not be infected yet/at all) then one Tablespoon of Epson salt per five gallons may alleviate the water buildup behind the eye. Do consider especially if removal to QT is not convenient or possible. Kindly, Anthony>

Septicemia <You actually have reached Steven Pro. Bob is away for awhile and Anthony Calfo and I are trying to fill his rather large shoes.> A client whose tank I maintain has told me he thinks he has an albino Oscar with septicemia. I haven't seen the fish yet, so I can't confirm. 150g tank with two Fluval 404's. <Is this all the filtration? Oscars are pollution machines that require massive filtration and frequent large water changes.> It has only been set up a month, but I did "seed" the Fluvals with a large amount of biological medium from a well-establish existing tank. Two weeks ago, the water conditions were fine, Ph = 7.0, zero readings on the ammonia, nitrites/nitrates. <Double check all four of the above. These things are usually brought on by high levels of dissolved organic solids which can be inferred by lower pH readings and high nitrates.> I know I'm not giving you much info. I'll stop by and check water parameters tomorrow and examine the Oscar. (it was introduced into the tank about 10 days ago.) Assuming the Oscar is indeed septicemia, what is your recommended course of action? I planned to due a regular 10% water change <How often? 10% per week?> at tomorrows visit, and will change more if the quality readings are off. I've never had a fish with septicemia in over 25 years in the hobby. Any advice you can provide with what little info I've provided you would be appreciated! Regards, Jay

Boiled Eel.. >Hi, >>Hello. >Wow incredible site. >>Thank you. >My sister has a tire track eel and it's sick, it has boils (?) on its back. That's how she described it to me. >>Sounds like ulcers, an open sore is my take on it.  This isn't good, though. >What might it be and how can we fix it? >>We see ulcers of this type most commonly on goldfish.  It's called septicemia (see here: http://www.fishbase.org/Diseases/DiseasesSummary2.cfm?discode=809 ) >Do you have any good references for info on curing disease/sick tire track eels? >>Not specific to tire track eels, but you can also search for treatments for SCALELESS fishes. >I read on your site that if it has sores it's likely to die soon? >>Maybe not so soon, but these afflictions can be very difficult to deal with.  It should NOT be treated in the main display, however. >She's very found of this eel as she says it has a lot of personality! >>I'm sure it does, and if you can, search further on http://www.fishdisease.net/ as well as looking for freshwater fish forums and sites.  Because these infections can by caused by many bacteria, treatment is rather like "blasting" with antibiotics.  Marina >Thanks, Cindy

Re: Gourami dwarf red sunset fishes turning white colour Thanks for your wonderful web site and service to all of us out here. Sometime ago I was reading somewhere about these fish on your chat pages, someone mentioned that this happened to their fish and I cannot recall the rest of info or even if there was an answer for it. Well it has happened to my two little fish I've had for about a year now. Please could you advise me where to get info if possible. < A whitish or cottony growth could be the result of a bacterial attack followed up by a secondary fungal infection. Try treating with Furanace. -Chuck> Many Thanks and again you have a great website.--mm

Rainbow Shark problem I have a rainbow shark that was in my 10 gallon (and was one of the few fish to survive that mistake) and is now in a 29 gallon.  Lately it seems to be thrashing around a lot for no apparent reason, but my real concern is it's back up around the top fin.  It looks like it is loosing scales, although I thought sharks didn't really have scales.  My test strip (Jungle) says the nitrate is just above 20mg/L, nitrate-0, very hard water and a ph right at 7.  I hope this is enough information. < You probably have a bacterial infection. I would recommend a 30% water change to reduce the nitrates. Service the filter to reduce the organic load in the system. Treat with Nitrofuranace to eliminate the scale /flesh eating bacteria.-Chuck> -Jackie

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