Please visit our Sponsors

FAQs on Characoids/Tetras & Relatives Environmental Disease

FAQs on Characoid Disease: Characoid Disease 1, Characoid Disease 2, Characoid Disease 3,
FAQs on Characoid Disease by Category: Diagnosis, Nutritional, Infectious, Parasitic, Social, Treatments

Related Articles: Characoids/Tetras & Relatives,

Related FAQs:  Characoids/Tetras & Relatives, Characoid Identification, Characoid Behavior, Characoid Compatibility, Characoid Selection, Characoid Systems, Characoid Feeding, Characoid Reproduction,

Many troubles possible... need to be cycled, stable... soft/acidic water; not much salt/s, no destructive tankmates,

Acestrorhynchus Falcatus nose anomaly.    12/3/14
Hello, assorted fish guru's of WetWebMedia. I have a weird question that I have searched ( almost) everywhere to no avail, for the answer. I have what they are calling a red tail barracuda, or dog cochorro, or all sorts of crazy names. I'm fairly confident that it is a Acestrorhynchus Falcatus.
<Appears to be>
He seems to have a bloated upper lip that comes down over the front of his mouth. Always did. I got him very early. Was wondering if you guys have any ideas. A mutant? Maybe an infected wound? Any help at all would be appreciated. You guys are the best. Thanks.
<The second guess I'd go with. VERY common for this and related species to injure their snouts... jumping, rushing into decor, tank sides. Nothing to do really treatment wise... and your present system looks large enough...
Thank you for sharing. Bob Fenner>

sick x-ray tetra, env. 12/6/11
today one of my 5 x-ray tetra is not swimming normal. kind of jerking around. like it can't use its tail. All other fish are fine. I do water changes once a week. .25 nitrates
<Do you mean nitrite... NO2?>

(I don't know why it doesn't come down...my tank has been cycled for 3 months)
<Usually insufficient biofiltration, circulation... See WWM re>
0 nitrites and 40 nitrates.
<Oh... maybe you mean/t Ammonia... toxic, as is your too-high Nitrate. Do read here:
scroll down to the yellow tray>
I just did a water change yesterday so I don't know why nitrates are that high?
<Read where you've been referred>
I don't see anything wrong with the fish like I don't see any disease or anything. could have just been sickly to begin with? but I have had them for 2 months with no issues. so what do I do? is it inevitable it will die? do I just let it die in the tank?
thanks! -Lauren
<Doubtful, read/act, and no and no. IF your water quality wasn't off as indicated by your measures of nitrogenous metabolites, I might suggest the one specimen had physically injured itself, had some sort of genetic anomaly. But you've got to address the lack of complete cycling here and cut the NO3 by at least half. Read on! Bob Fenner>
Re: sick x-ray tetra 12/6/11

Yes I did mean .25 ammonia. I have an Aqueon 30 quiet flow for my 20 gal tank. But I haven't changed the filter cartridge in a while....maybe that's why my levels are high. Thanks!
-Lauren Jerry
<I'd add another filter... and read where you were previously referred.
Your fishes are in imminent danger of poisoning by their own wastes. BobF>

White patches spreading on fish 6/21/10
I am having a problem with my rummy nose tetras getting whitish patches.
<I can see.>
This tank is cycled, 10 gal,
<Much too small for this species; Rummynose tetras are fairly demanding fish, and suffer in small tanks -- anything less than 30 gallons, to be honest -- and cannot abide immature aquarium conditions.>

I check the ammonia every week and after 3 weeks I had .50 so it has had a recent water change.
<If the aquarium has had non-zero ammonia levels for three weeks, that's very likely the cause of the problem here. Is the tank actually a mature one? In other words, one more than 3 months old? Or is it a new aquarium?>
The pale patch on the fish was noticed soon after I bought the school of four tetras about 4 weeks ago,
<Again, these tetras aren't forgiving of mistakes. Keeping fewer than 6 tetras is always a bad idea, and with Rummynose tetras your scope for mistakes is minimal. Social stress could easily make worse any other problems.>
I did some treatment with Maroxy and Melafix assuming it was fungus and it did nothing-didn't grow didn't shrink- so I quit treatment after a week and decided it just had odd coloring.
<Is not odd colouring; this is some type of bacterial infection, Finrot-type thing. Needs to be treated with a suitable antibiotic PLUS appropriate "fixes" to these tetras' environment.>
Now the whitish patch is growing and one other tetra is showing a small spot of it on its head. The fish still all have nice red faces- they get pale if they are stressed or sickly or so I am told.
<They can do, but pale heads aren't the only signs of sickness, anymore than sneezes are the only signs that humans aren't well.>
I have researched on line the only thing that seems to match is Columnaris but the fish is still active and not acting sick. My experience with Columnaris is that it is fast and deadly-had two new betas die overnight from it in March and never bought fish from Petco again- so I don't think it is Columnaris;
<Could be Columnaris, but you can't really be sure without microscope work.
Certainly bacterial, so either way, treat with something that treats Finrot and Columnaris.>
what do you think it is?
<Stress-induced opportunistic bacterial infection. You've kept these fish badly, and now they're dying. Fixing the environment -- better water quality, larger tank, more specimens -- will save them, alongside appropriate medication.>
Thanks for any help.
<No problem.>
<Cheers, Neale.>

Help with Rosy Tetras, sys.... env. hlth. 11/20/09
Hi Crew,
<Hello Chris,>
Hoping you can give me advice on my Rosy Tetras.
<Will try.>
Tank set-up:
20 gallon planted tank
<20 US gallons? A bit on the small side of this species... will hide a lot.>
Ammonia 0, Nitrites 0, Nitrates 8 -10
15-20% water change every week (diligent about water quality and testing)
Temp 78
Community tank with Corys/Otos/2 swords/3 Rosy Tetras and 6 Serpae tetras, and a Farlowella
<Serpae tetras are aggressive nippers, and not my first choice for the community tank (English understatement... wouldn't let them anywhere near community fish).>
I've had my 3 Rosies for 1-1/2 years and realize now that I should be keeping them in larger groups, but I think I would be overstocking if I added 3 more fish.
<Indeed... but my prime concerns are that some of these species, the Rosy tetras and the Swordtails, really do need more swimming space.>
Lately one has been hiding, and this fish, along with one of the other Rosies, are losing colour and appear to have some blotchy darkness/redness internally. It seems in the gill area as well as toward the middle of the fish. It is very subtle as is the colour loss (at first I thought I was overanalyzing), and I wonder if I'm seeing the start of some sort of infection due to the stress of bullying, as one of these Rosies has started harassing the other two...no nipping, just swimming quickly at them until they hide. All 3 are eating normally, and all fins look good.
<Likely a symptom of general stress, though whether it's the size of the tank, or nipping from the Serpae tetras, I can't say. To be honest, if there were six of them in a 20 gallon tank without the Serpae tetras, I think they'd be okay, but the Serpae tetras really aren't good choices for keeping alongside Rosy tetras.>
If this is what the problem is:
(1) If I remove the "bully" (and hope that the other 2 recover) would he survive in a 10 gallon tank with 4 Corys and a dwarf Gourami? Would the Gourami be bullied too? Or would it be better to move the Gourami to the big tank and put the bully Rosy in the small tank with the Corys which he doesn't seem to bother with (so far).
<Not a good idea. Keeping these fish in a 10 gallon tank really would be pushing your luck. Removing bullies rarely works in situations like this, where the problem is the group is too small for normal schooling behaviour.>
(2) If I remove the two Rosies in question and quarantine them, I would have to put them in a small 5 gallon tank (heated and filtered). Would this small tank stress then further?
Should I medicate the water?
<Not unless you detect symptoms of a particular disease.>
Thanks in advance for your advice!
<You're welcome.>
<Cheers, Neale.>
Re: Help with Rosy Tetras 11/20/09

Hi Neale,
Thanks for the quick response to my question re my Rosy Tetras that look like they are losing colour and have some darkish/red internal problems.
<See, this is the thing... all these tetras can change their colours significantly depending on mood. Their colours can range from pale salmon pink through to almost a fiery red. Further, the idea of "internal
problems" is common parlance for "haven't a clue what's wrong". It's actually pretty uncommon for fish to genuinely have some mysterious bacterial or viral infection. (Some exceptions though, like Dwarf Gouramis
and their viral and Mycobacteria infections.) Anyway, while it's not impossible that your fish have some bizarre bacterial infection, I'd tend to bet against it. Evaluate all the other possibilities. Unless there are
obvious symptoms of a bacterial infection -- such as loss of appetite --
I'd tend to assume this problem was more behavioural than anything else.>
I did some more homework and the fish I identified as Serpae tetras are actually red phantom tetras - sorry!
<Ah, now things become interesting. Red Phantom Tetras, Hyphessobrycon sweglesi, formerly Megalamphodus sweglesi, are not a tropical fish. They need fairly cool conditions, 20-22 C being ideal. When kept too warm they never do well, and tend to be short lived. So instead of 5+ years, you get a couple of years out of them. So while ideal for other low-end tropicals like Danios, Neons and Peppered Corydoras, you wouldn't keep them with, for example, Dwarf Gouramis or Angelfish, both of which need above 25 C to be happy. It's a very common mistake to assume tropical fish all like really warm water; many of them don't.>
The receipt I had filed away only said "tetras" and I thought Serpaes looked like them but it is in fact red phantoms. I've had them for two years and they are extremely peaceful little guys.
<Yes, they are a nice species.>
Re the swords and the rosy tetras, I agree that a 20 gallon is too small and if I were to do it over again I would make other choices.
If you think I should add 3 more Rosies to try and help the 2 that are being bullied I will but worry that I am going to be overstocked. What do you think?
<Worth a shot.>
In my 20 gallon I have:
6 very small Oto cats
<These like cool water too.>
1 Farlowella
<As do these.>
6 Corys (3 are very small - I forget the name - and 3 are peppered so are a little larger)
<And these too.>
2 swords (fairly large swords)
<Also should be kept below 25 C.>
3 rosy tetras
<These do need middling temperatures, around 24-26 C.>
6 red phantoms (very small)
<As we've seen, like things a little on the cool side.>
Would adding 3 more rosy tetras to this mix make it a dangerous load?
<Assuming robust filtration, I don't think you'd be running too much of a risk.>
As I mentioned I do weekly water changes and it is has been years since I have had a water quality issue but am concerned.
I am concerned that the internal discolouration/redness and colour loss of the two tetras will get worse if things remain status quo.
<I would be worried too.>
Thanks again!
<Good luck, Neale.>

Neotrop community tank; sickness, death, but no useful data - 10/24/09
I have 55 gal freshwater tank with Black, Red, and Gold Tetras 1 Pleco and 2 Cory cats.
<Hmm... not really sure what these "tetras" of yours might be.>
The Tank has been going for about a year and I haven't lost a fish in about 10 months until about 1 month ago. I lost 2 black Tetras in a few days with no on obvious signs. One of my reds lost color and was having labored breathing and died about 2 weeks later. Now one of my Golds is showing signs of labored breathing and has raised scales on his sides all others seem to be doing fine. NO2, NO3, KH, GH are all within normal ranges
<What are "normal ranges"? The thing is, without knowing the actual values, I can't say anything sensible. But let's recap. For most South American tetras and catfish, you're aiming for these values: Zero ammonia, zero nitrite, carbonate hardness around 5-10 degrees KH, and a general hardness around 5-15 degrees dH. The pH should be around 6.5 to 7.5.>
I do about a 20% water change every two weeks and use AquaSafe and Neutral Regulator by Seachem at changes
<Please, check the water chemistry/quality values are as stated above.
Usually, when random species start dying for no obvious reason, and the symptoms are nebulous things like dropsy and heavy breathing (as is the case here) then environmental issues are to blame.>
What do you think is Killing my fish.
<Cheers, Neale.>
Re: Neotrop community tank; sickness, death, but no useful data- 10/25/09

Thanks for your time and your response. I'm sorry I can't give you a better name on the tetras but I only know them as Black, Gold and Red long fin Tetras. The water chemistry is NO3 = 20ppm, NO2 = 0ppm, PH = 7.0, KH = 40ppm, GH =60ppm, Ammonia = 0ppm.
<Sounds mostly okay. The water hardness is low, and while not in itself a problem, do understand that in soft water the pH is prone to dropping, so I tend to recommend people maintain freshwater communities at slightly alkaline conditions, around 4-6 degrees KH (about 70-110 mg/l CaCO3).>
These values are reached using API test strips. There have been no new fish added to the tank for at least six months. There are two filter systems on the Tank. I know that without seeing the tank or fish that a diagnosis difficult. I have rechecked the water values and they are as stated I don't know the conversion for the KH and GH from ppm to deg.
<Easy: 1 degree KH is 17.9 mg/l.>
however as I stated the API kit I use says these values are within the normal range for tetras.
<Indeed, but what fish experience in the wild isn't necessarily what's easiest to maintain in captivity. Do read here:
I know that Tetras aren't the most exotic of fresh water fish but I enjoy them and hate to loose any. The only fish that seems to be exhibiting any symptoms at this time is a Gold Tetra about 3"long, the symptoms are
labored breathing raised scales and I noticed 1 red spot about 1mm on one side just below his dorsal fin and a lack of appetite, all the other fish seem to be behaving normally and appear normal. I hope that I have given you enough information to give me a suggested course of action to save my fish. Thanks again for your help.
<Difficult to say what the problem is here. Heavy breathing tends to imply changes in environmental conditions, typically to the worse. So for example non-zero levels of nitrite and ammonia, or sudden changes in pH, or poisoning of the tank with insect spray, paint fumes, or whatever. Raised scales are associated with Dropsy, and that's a symptom of organ failure, typically the "end game" of a systemic bacterial infection or similar. Red spots on the body are inflammations or open wounds. These can be caused by all kinds of things, from physical damage through to certain viral and bacterial infections. So there's nothing here that yells out the name of any one problem. My instinct here would be to do a big water change to flush out any potential toxins (say, 50% today, and another 50% tomorrow) taking care that water chemistry of the new water was close to the water chemistry of the old water. I'd give my filter a clean, just to make sure it's working properly. I wouldn't feed the fish. I'd check the heater was at the right temperature. I'd look over the tank for signs of serious decomposition: dead fish, uneaten food, dense clumps of algae, dead snails, etc. I wouldn't treat the fish until I had a clear idea of what the problem
might be; most medications are toxic to some degree, and a "scattergun" approach rarely works out the way you'd like. Cheers, Neale.>

HELP!!!! Massive Tetra deaths, need help tonight! 10/23/07 Hey guys, <Hello,> sorry, I'm not gonna spell check this, hopefully you can get back to me tonight, and don't worry, I wont be offended if you don't post this on the FAQ's.... <Hmm... not sure it works this way.> I came home today to find 11 out of my school of 23 Glowlight tetras floating. they were all alive and fine as of 8 am this morning, and when I got home at 7 they were floating with bulging bellies (some were gutted with their entrails hanging out...) am at the north end of the san Diego fires right now (not in the path, but we might be evacuated tonight) I'm not sure, but I've heard of power outages in the area, so the tank could have been un powered for quite some time... I did a 1/3 water change yesterday, the same way I always do, with the same water treatments. I'm not sure what caused this, and I might be evacuated tonight and unable to return for a day or so. please let me know if there is anything I can do to protect the rest of the tank residents when/if I am gone I'd appreciate it! <Massive sudden deaths of fish can be caused by two different things. The first is a crash in water quality. While filtration is certainly one thing to check, the other is pH; tanks lacking carbonate hardness are intrinsically "unstable". On top of this, all tanks have a tendency to become acidic. So without a carbonate hardness "reserve" in the water to mop up those acidifying chemicals, it doesn't take much to tip a tank over the edge into a sudden pH drop. I've seen tanks go from pH 7 to below pH 6 within a couple of days. There's a bit of a positive feedback too -- acid-hating plants, like Vallisneria, will die off when the water becomes acidic, and as they die, they decay and produce more organic acids, and that speeds up the acidification process even further. This is why I consider hard water a "blessing in disguise" despite the fact it isn't ideal for many aquarium fish: for all its shortcomings, hard, alkaline water is stable and resists water chemistry changes. In the meantime, check for possible sources of acidification: dead animals, rotting plants, etc. The second thing that causes sudden fish deaths is toxins. Insecticide, paint fumes, even tobacco fumes can cause real problems. Adding non-aquarium safe objects to a tank, such as wood that's been treated with pesticide, is also dangerous.> thanks, and be safe Bob, I know you're right in the middle of this too. <Anyway, if you are worried about possibly doing without power for periods of time, then invest in some large lidded buckets. I have 5 gallon buckets for this. Into each, put small groups of fish. Partially fill with water, and replace the lids loosely so air can get in. You can then move these to a warm part of the house. Changing water in the buckets on a daily basis is essential. Why do things this way? There reasons: water changes will compensate for filtration; and secondly deaths of fish in one bucket won't place any of the other buckets at risk, so you can "micromanage" fatalities; and finally you don't have to deal with dead/dying plants, snails or whatever. You can easily replace those if you want, but should the fish be in there when they die, the decay mops up oxygen and stresses the fish. I've safely looked after fish this way for days on end. Good luck, Neale>
Re: HELP!!!! Massive Tetra deaths, need help tonight! 10/23/07
Hmmm, so it probably has something to do with the peat I added to the filter about a week and a half ago to help soften my very hard tap water. and then changing 12 gallons out of 36 with water not treated with peat? it looks like I will have to just stick with stable, hard water. is it best to just pull all of the peat out immediately or gradually? <This sounds very likely to be the cause of the problem. Sudden changes in hardness and pH, even from "bad" to "good" values, can be lethal. I don't personally like adding peat to aquaria as a softener. Peat is very unpredictable, and once the water starts to soften, the pH can drop precipitously. Much better to have the aquarium filled with chemically inert materials (silica sand, gravel, etc) and then adjust the water outside the tank, e.g., by mixing hard water with a certain amount of rainwater or Reverse Osmosis (RO) softened water. (Note: not water from a domestic water softener; while lacking in carbonate, this has high levels of chloride, and simply isn't "soft water" as aquarists mean it.) Once you have the water you want, you can add this treated water to the tank in increments, allowing the fish to slowly adjust to the new conditions over a few days. Since there's no peat actually in the tank, the pH and hardness in the tank should be basically stable. For a standard community aquarium, you only need to slightly soften hard water for good results. A pH around 7 and hardness of 10 degrees dH and 5 degrees KH is just about perfect for most community fish. There's no real benefit to softer, more acidic conditions unless you're spawning exceptionally sensitive fish such as Cardinal tetras, wild-caught Discus, Chocolate gouramis, Rasboras, etc. For simple maintenance, the above conditions are just fine. Indeed, some degree of (carbonate) hardness is desirable because it inhibits the background acidification that happens in all aquaria over time. In the meantime, if your fish are alive and feeding, assume they've adjusted, and make adjustments back up to your hard water conditions by doing no more than 20% water changes per day. Slowly but surely is the way to win the water chemistry game. Either that, or don't play at all, and stick with your baseline tap water conditions. Hope this helps, Neale.>

Mysterious repeated hatchet fish death  10/18/07 Hi, I hope you can have an answer. <We'll try.> We have a 10 gallon tank with live plants, 3 platys and 3 hatchet fish. two day after we introduced the hatchets, we found one of them dead. Went to the store bought another one, next day dead. <Hatchets aren't the easiest of fish. Which species are we talking about here? There are two common types, Marble hatchets and Silver hatchets. The Marble hatchet is Carnegiella strigata and it is small, mottled brown, and quite delicate. It needs to be in groups of 6 or more to have any chance of surviving. In ones and twos they just die. Not recommended for your tank simply because they will feel trapped and get stressed. When stressed, they jump at the glass lid or lamps, and damage themselves. The Silver hatchet is Gasteropelecus sternicula. It is larger, silver, with a blue horizontal band on the flanks. It is basically hardy once settled in, but mortality during the first few weeks can be very high. Given its adult size and high activity level, not really an option for a 10 gallon tank.> The water is fine, Ph between 7 and 7.2 temperature around 76-78. The community is fine and the plant are thriving. We are feeding them with Spectrum the small fish formula. We thought they might be jumping and hurting themselves on the hood. <Happens.> The deaths happened during the day. Thanks a lot Emanuela <Give up with Hatchets. Your tank is not really suited to hatchets. While lovely fish (I keep Silver hatchets) they are far from easy fish and best suited to expert fishkeepers or aquarists prepared to set aside a large, quiet, thickly planted tank where they can be kept in large numbers. If you want a surface dweller of some type, look at something like Sparkling gouramis (Trichopsis pumila) which are hardy, colourful, and do well in small tanks. Cheers, Neale.>

Mouth disease on tetras  6/4/07 > Hi Guys, <Hello.> > I have a 80lt f/w tank with a few tetras, a bristle nose sucker fish, two clown loaches, some dwarf Gourami's and a couple of mollies. <All sounds fine except the mollies probably want brackish water, not freshwater, and the clown loaches grow very big (admittedly slowly) and even a tank twice the size of yours will be too small for them in the long run.> > Recently the tank started smelling like dirt and one of the tetras died with a white growth that looked like it had grown over its mouth. <The white growth was almost certainly "mouth fungus", which is a bacterial infection almost always brought on by poor water quality.> > We cleaned out the canister filter as it had started to become noisy due to a build up of gunk. <OK. But cleaning a filter should not mean wiping out the bacteria in the filter media -- so only ever clean the media in buckets of aquarium water.> > A week later another tetra was found with this growth. <So, the problem wasn't fixed.> > I removed the fish, did a 40% water change and started using a Aquarium Pharmaceuticals 'Melafix' of 10ml per day with a 30% water change every 7 days as directed. <Melafix will have no effect at all on mouth fungus. Melafix is the aquarium equivalent of antiseptic cream -- it helps keep cuts and wounds from being infected, but don't expect too much from it. Your need anti-mouth fungus (a.k.a. anti-Columnaris) medication.> > This was about 2 weeks ago. <Mollies are nitrate intolerant when kept in freshwater aquaria. If I had a penny for every molly that died from being kept in a freshwater rather than brackish water tank I'd be richer than Bill Gates. Needless to say, none of your other fish are salt-tolerant. Yet again, an example of choosing fish before researching them.> > Since then two mollies have died, with no signs of disease and last week I noticed one of the Gourami's turned from a red color to black. We did a water change and soon after this it returned to its normal red color. <Fish sometimes change colour when stressed, including by deteriorating conditions. It sounds as if you have water quality/chemistry issues.> > Ph is about 7, at the start of the issues it was around 6. <Mollies need a pH of AT LEAST 7.5. All your other fish want a pH around 6.5 to 7.0. Any time the pH of an aquarium drops from 7 to 6 quickly, it means you have major problems with the aquarium. We need more data here: what is the hardness? What is the pH/hardness of the water straight from the tap (faucet)? What are the nitrite or ammonia levels?> > Do you have any ideas?? <Sounds to me as if your tank is inherently unstable. Likely a combination of acidification through decaying organic matter in the tank (overfeeding, under cleaning) and not enough buffering capacity in the water. Various solutions depending on the specific problems. But we need more data to pin down precisely the causes. In the meantime, reflect on the stocking density, your maintenance regime, what (if any) buffering exists in the aquarium.> > Cheers and hello from Oz, <Cheers, Neale>
Re: Mouth disease on tetras  6/4/07
> Thanks for the quick reply Neale. <No problems.> > I did have my students feeding the fish, and I did suspect they were over feeding. They backed off the feeding about a week ago. I've ordered an anti-mouth fungus too. I vacuum the gravel every 2 - 3 months should I increase this to monthly? I also do a water change of about 30% monthly. <Cleaning the gravel is a function of how dirty it gets. In a regular community tank with small fishes, what you're doing is fine. In the tank with messy fishes and a lot of detritus in the gravel, step the cleaning up. When you siphon the water out during water changes, it's always a good idea to "Hoover" the gravel as well, and suck up faeces, decaying plant material, uneaten food, etc.> > Can you please explain buffering capacity? <Very simply, buffering is the ability water has to resist chemical change thanks to the water containing certain dissolved chemicals. Not all chemicals are buffers though. Table salt NaCl (sold to aquarists as "tonic salt") has no buffering capacity at all. It is essentially things like calcium carbonate (lime) that buffers water to an alkaline pH, or organic acids (commonly from peat) that buffer water to an acidic pH. Typically, aquarists buffer to a slightly alkaline pH because this works well for the widest variety of fishes while remaining chemically quite stable. Acidic pH systems tend to be unstable, becoming increasingly acidic over time unless carefully monitored. Anyway, provided you have a "medium hardness" on whatever hardness scale your test kits measure (say, 10-15 degrees General Hardness) you don't need to worry about buffering. It'll all happen in the background, and regular water changes will top up the buffering capacity of the aquarium without any further work from you. If the hardness is lower than this, i.e., you have soft water, then you may need to do some work. There are multiple solutions. You could keep brackish or hard water fish, for example. By adding marine salt to a brackish water system, or Malawi/Tanganyikan salts to a livebearer or African cichlid system, the buffering would again happen in the background all by itself. If you have soft water and want to stick with the soft water fish, such as Neons, barbs, Corydoras, etc., you need to monitor the pH on a weekly basis until you get a feel for the trend in pH changes that happen in your tank. Large water changes weekly should prevent drastic pH swings. There are pH 6.5 buffering solutions available. You simply add them to the water with each water change. Alternatively, you could do what I do with my soft water tanks, and that is mix 1 to 3 parts soft water to 1 part hard water. Most good freshwater aquarium books should go into the water chemistry issues in depth.> > Cheers and thank you for your advice. > Mike <Hope this helps. Neale>

I am obsessed with keeping freshwater cardinals! I just can't keep them alive!   5/13/07 Hi! <Hello!> Hope all is well with you.  I have a question I hope you can help me with. I have had reef and saltwater tanks for a couple of decades, and I do pretty well. I even have a 600 gallon one in my kitchen wall! <Sounds nice. Though if you prepare sushi in the kitchen, I imagine the fish get rather nervous wondering if they're next...> But I am obsessed with keeping freshwater cardinals! I just can't keep them alive! <I we talking those neon tetra look-alikes, Cheirodon axelrodi, or the freshwater examples of the marine cardinals such as Glossamia aprion, the "mouth almighty"? I assume the tetras.> I have a 45 gallon tank with a sump. (an old reef tank). I had it setup with a BioWheel, and gravel on the bottom. I suctioned the gravel monthly, did a 33% water change monthly, and no luck with the cardinals. <Cardinal tetras can be tricky for a variety of reasons, but once settled in they're basically tough little fish. The main problem in my experience is Neon Tetra Disease (NTD), which works its way through cardinal tetras at about 50% mortality, i.e., if you buy 20 cardinals, and you get the dreaded NTD, you can lose up to half of them. Better than Neons, where you lose all of them, but still annoying. Another issue with cardinals is they are all wild-caught. <<Mmm; no; bred in vast numbers in the orient for the ornamental trade. RMF>> In fact, they're the most numerous exported tropical fish from South America. Anyway, by the time they reach the market countries around the world, they might not have eaten for weeks. My guess is that healthy, well-fed cardinals are more or less NTD resistant, but when weakened and cooped up in a retailer's aquarium, they are far more susceptible to this disease. So as with any wild-caught fish, buying when a new batch arrives can make sense, and then quarantining and feeding on a variety of live/frozen foods makes all the difference.> I then added an undergravel filter (I know....dumb idea, but I was desperate!) <There's nothing intrinsically wrong with UG filters. They do a good job of maintaining water quality. The problem with UG filters is their incompatibility with aquascaping and rooted species of plants more than anything else.> No luck. Nitrates off the chart. Dead cardinals. <Odd, given how small cardinals are. They don't eat much (and don't need to eat much, either). They're classic "pinch of flake a day" fish in my book. When you say "off the scale" you mean above 100 mg/l? What is the nitrate level of the water out the tap/faucet? I have to confess to keeping mine in rainwater with a bit of tapwater added. Seems to work well.> Someone suggested bioballs.  Would not that make the nitrates even higher? <Worth trying I suppose but I don't find nitrate removal systems in freshwater tanks to be of much value. Freshwater fish don't care that much provided the rise in nitrates is slow, and even between 50-100 mg/l you shouldn't get mass die-offs of fish except with certain species (Tanganyikans for example). Simple water changes are, IMO, a better approach to nitrate management, and the filter is best devoted to biological filtration, i.e., ammonia/nitrite management rather than nitrate.> I have used Amazon rain additive (is that stuff any good?) <Not really. Looks nice, but doesn't really do anything if you have hard, alkaline water. In softer water, may help acidify the water a little, but approach the concept of acidifying water with caution, as it's easy to mess up.> No luck. PLEASE do you have an ideas?  Thanks! <Have a read of this: http://www.wetwebmedia.com/ca/volume_2/cav2i3/cardinal_tetras/Cardinal_Tetras.htm for some more ideas.> <Cheers, Neale>

Molly and Neon Tetra Health Questions, env.  3/16/2007 Dear WWM crew, <Ching> I love your website and learn a lot from here. Thank you. <Welcome> I have a 15 gallon tank with 2 Cory catfish, 3 black mollies and 7 neon tetras. <Mmm... the Cats and Neons like very different water conditions than the mollies... soft, acidic, much warmer... no salt...> Environment: Water PH: 8.0 (Our tap water is pretty hard.) <I'll say! About the same here in San Diego> Temperature: 25~26 C Nitrate: 20~40 ppm <Way too high... a source of stress...> Nitrite: 0 ppm Ammonia: 0 ppm One male molly has "obvious" mouth fungus and noticeable grey spots on his body. As I heard Cory catfish and neon tetra do not like salt, I did not add aquarium salt to the tank. <Good> I used Melafix and Pimafix together to treat the black molly. The second day and third day I could see the improvements and thought the medicine worked great. <Mmmm> As the medicine indicated we can use it when intruding new fish to the tank, so while during the course of Molly's medication (on the fourth day, I think) I added 4 neon tetras to the tank. The 7 neon tetra were doing fine and schooling around together. The black molly seemed to be getting better too. However, yesterday (the 8th day of the medication) black molly's mouth started to show the fungus again and I saw a couple of grey spots on his body. Should I use other medicine, stronger one? Or I should continue the ones I am using? <I would separate the molly/mollies, treat it/them with salt... Keep it in another setting> Today (the 9th day) I saw a red spot on one neon tetra's body, which is near the tail. I am not sure what it is an have no idea what I should do. It looks like human's bruise just the color is red not purple. Anything you could suggest? <Yes... to modify their water chemistry (w/o the Mollies present)... to be softer/more acidic (pH below 7.0)...> I have had this tank just for two months and enjoyed it a lot. But, there's still so much to learn to keep my fish healthy. <Lots of valuable lessons about life...> Thank you again for all the information you provide on the site. It is really helpful! Yours truly, Ching <A pleasure to help you, Bob Fenner>

Blue Neon Tetras : Old or ill?  - 05/09/06 Hi, <<Hello, Francesca. Tom with you.>> I am a first time poster on this site - you seem a lot less smug than other sites and I would appreciate help rather than finger pointing!   <<I lost whatever "smugness" I may have had years ago. :) As for "finger pointing", let's see what you have to tell us.>> I have a 95 litre tank which happily (usually) houses 8 blue Neons and cardinals, 3 black tetras, 3 glass catfish, 3 swordtails, 2 small albino Corys, 1 golden sucking loach (who knows his place and is not a bully), 1 upside down catfish, 1 fat apple snail and two small but adult silver sharks who we inherited with the tank.  Some were residents of the tank when we took it on (the bigger ones) and others have been added over the course of about a year.  We are expecting a new tank, about double the capacity, very soon, since we are aware that the silvers require more space really. <<Excellent. If you could "lock down" the specific species of "shark" that your "Silvers" are, we could add a little more detail. For example, what are known as Silver-tip Sharks (among other names) require vastly different water conditions than the other fish in your current tank need. Might be a problem down the road...>> They have all been cohabiting merrily for a number of months now.  They get about 15 to 20 per cent of their water changed on a weekly basis, are regularly dosed with salts and their new water is dechlorinated at every change.  The PH remains at roughly 7, the ammonia level as of last night was 0.25ppm, the nitrite level was negligible and the nitrate level (whilst higher than I would like it) was at an apparently safe 35ppm. <<Okay. Ammonia levels and nitrite levels above "0" are not good. (I'll get to this later since it has a direct bearing on your question.) Nitrate levels are "safe" up to 40 ppm for "some" fish. Others can't tolerate these levels over a sustained period. Cichlids, for instance, require low levels of nitrates as some diseases attributable to nitrates are known.>> The problem is this.  Three of the blue tetras seem to be unwell.  They are showing black discolouration on random areas of their bodies, although this does not appear to be fungus or algae, but rather a genuine change in colour.  They do not seem to be wasting away or becoming thinner, but instead seem to be kind of lumpy, again in random areas. <<Black discoloration can be a sign of chemical burning, i.e. from ammonia/nitrite exposure, that is actually in the process of healing. Usually, this will occur around the gill plates. The change in normal coloration can be expected when a fish is stressed.>> With the exception of one they are schooling, swimming and feeding as normal, but one is showing possible swim bladder issues.  He is twirling and swimming on his side, and avoiding the company of the others.   <<Again, this can be due to stress and toxic poisoning. Some fish are more "susceptible" than others.>> I have looked at a number of sites with partial descriptions of these symptoms, but nothing complete.  They are showing some symptoms of Neon Tetra Disease, but lack the significant seeming white discolouration.   <<I would discount this. From personal experience, your fish would be dying/dead right now. Trust me.>> I do not know how old they were when we bought them, but they were fully grown.  They were brought from an aquarist shop specifically chosen because they seemed to care about the welfare of their livestock over that of their profit, but I did not ask their age at the time of purchase. <<No worries. I'm glad you found someone to trust.>> Are my fish ill? <<In part, I would say that they are.>> If so, is there anything I can do to help them? <<Easiest treatment in the world. Water changes. Get the ammonia/nitrite/nitrate levels down. Start with a 50% water change (40 litres). Also, check your filtration. Don't believe that a filter rated for 90-100 litres will actually do the job. Oversize it, as you should with your new tank.>> Are they just old? <<Perhaps, but there are still things you can/must do.>> They are small, so I suppose they have a limited number of heartbeats like the rest of us! <<That's why I don't exercise, Francesca. I don't want to use up the heartbeats I have left! :)>> Please help me as I really do not like seeing my boys ill, Francesca <<Hopefully, I have helped. Best of luck. Tom>>
Re: Blue Neon Tetras : Old or ill?
 - 05/09/06 Hi Tom, <<Hello again, Francesca.>> Many thanks for all your help.  You have no idea how relieved I am that we can probably discount NTD.   <<Very glad to be able to help. Having had personal experience with NTD, I know exactly how relieved you are.>> We will get on with those water changes, and have found a nitrate/nitrite (and, by definition, ammonia) teabag thingy for the filter. <<If I may, Francesca, rely on the water changes rather than your new filter insert. I suggest this because you don't want to starve the bacteria that feed on ammonia and nitrites. There is an "irony" here, which is that these filter media will work. The downside is that they may not let your tank reach its "potential" so as to become "self-sustaining". Your parameters aren't so far out of line that you have an "emergency" on your hands. The long-term benefit of letting things run their course is that you won't have to "toy around" with your tank. Much easier on you in the long run.>> We will upgrade the filter ASAP.  The deal we have seen on the tank includes a filter so we may be able to upgrade this at that point. <<This sounds very good. I love upgrades! :)>> Thanks again for setting my mind at ease. Fran <<Happy to do so, Fran. Tom>>

Fading Serpae Tetra  - 2/15/2006 I recently bought 2 Serpae Tetras about a week ago.  They are in a 10  gallon tank with 2 fancy tail guppies. <Like different water...> All are doing fine, but noticed this  morning one of the Tetras looks like it's fading.  He's not the bright  orange and black he was before.  What do you think could be the  problem?  Thanking you in advance..... Jenny~ <The Tetras "like" soft, acidic, warm water (80's F.), the guppies, hard, alkaline, cooler water... Bob Fenner>

Dying neon tetras  02-05-06 Help! two weeks ago I did a complete change out of my 10 gallon tank, saving off half the water and rinsing the new gravel and furnishings well and added a bubbler. <Better to limit such changes to one quarter if at all possible> The tank is inhabited by 5 neon tetras, 5 harlequins and 1 Pleco. <Too small a tank for the last> the water I added was conditioned by Aquafresh (or something like that) <At least they'll have minty breath> and the original water was replaced as well. for two weeks everything was fine, <Only apparently> but yesterday one of the Neons became bloated and started swimming sideways. I removed it from the tank and put it in another container and it was dead by morning. Today, I've noticed another neon started to exhibit the same symptoms. The harlequins seem to be just fine. I noticed a rust colored deposit building up on the new furnishings. what is this deposit and what is happening to my Neons? any advice you can give would be splendid! thanks, Chris <The Neons don't "like" your water... or this much change this fast... Perhaps your system is "re-cycling"... also much harder on small characins than minnows... See WWM, fishbase.org re their water preferences. Bob Fenner>

Tetras lost to a new tank Gwen,   Thanks for your fast reply - I appreciate your advice.  Unfortunately,  I think I will stay away from tetras because (maybe the water is too alkaline for them) I lost 3 different kinds of tetras when I started the tank 6 months ago. Another option might be some colorful guppies but I am concerned that they would need more salt in the water than I think some of the other fish would tolerate.    Thanks again.  Beth    >>Hey Beth :D Don't be so hard on the tetras :) You may have lost them simply because it was a new tank set-up. Tetras are normally more resilient than most other species of fish, and are quite easy to keep. By the way, guppies do not need salt in the water. Most people think that salt prevents Ich, or fungus, or does some other magic thing, but the fact is that most freshwater fish do not need salt added on a regular basis. It CAN be used medicinally, to cure such diseases, but salt should only be added when you are treating something specific. My advice to you would be to re-think the tetras, like Pristellas, etc, and guppies :) Have fun! -Gwen

Dying neon tetras Hi there, <Hi there...this is Jorie, and I'll try to help...> Have just come across your site and trawled it for any similar problems to mine, but couldn't spot anything, so I hope I'm not going to waste your time, but here goes! <You certainly are not wasting anyone's time - we are here to help you!> My fiancĂ© and I purchased a 13 gallon tank about 3 weeks ago and set it up as follows: washed gravel in water till it ran clear, washed resin tank ornaments in the same way. A couple of plastic plants, but mostly real plants (some sword grass and sword plants, at least that's what they said they were in the shop).  We added the tap water and treated it with AquaSafe to dechlorinate, etc. following the instructions on the bottle. We added some AquaPlus water conditioner and we also added a little plant food that said it was safe for other tank inhabitants and followed the instructions in both cases carefully.  We have a mechanical, biological and chemical filter that we checked was the right size for the tank, and a heater that keeps the water at a constant 78 degrees Fahrenheit.  The filter also has an attachment that can further oxygenate the water (little pipe attachment to pump out more bubbles).  Also have a hood and light for the tank. We cycled the tank for these weeks, and before we put any fish in we checked the ammonia, nitrite, nitrate and pH levels: ammonia, nitrate, nitrate were 0 and pH at 7.5. We live in Glasgow in Scotland and our water is quite soft. We also added some AquaPlus water conditioner the morning before the fish went in, because it recommended doing so for new fish. We bought six jumbo neon tetras yesterday afternoon - floated the bag for half an hour to get the temperature even for them, added some tank water gradually over another half an hour and then released them. They looked pretty happy, we left the light off to let them settle down and didn't feed them straight away for the same reason, feeding them a tiny amount about 2 hours later. Just before we went to bed we checked on them, and two seemed listless and gasping a little, but still able to swim, not just floating. This morning 2 were dead upside down on the tank bottom, and this afternoon two more. We did another water check and the levels were still fine. The poor guys looked physically ok when they died, apart from being a little pale - you could still make out the bright colours on their bodies. They didn't appear bloated with no cuts or gashes and seemingly normal gills. No signs of fungus or spotting either. When I was keeping an eye on the second two that died later, they seemed to get listless and were floating about the main body of the tank rather than swimming in the plants like the others. They also looked to be gasping a little.   I really don't want to be doing something wrong and be unknowingly hurting the wee fellas. The last two seem ok at the moment, although one swims about more than the other.  Do you think it could be something they had already from the shop, or am I doing something terribly wrong? Do you think I need to get them some medication, only I am reluctant to do so when they don't look hurt or diseased and I might do more harm than good? Any advise greatly appreciated, Charlotte <Charlotte, I'll be honest, I'm a bit mystified myself as to what's going on! I read your thorough narrative above, and very honestly, you did absolutely everything I typically suggest to newcomers, from rinsing the gravel, cycling the water, keeping the temp. constant, etc. The one thing that I'd suggest you measure is the water's oxygen level; you mention that you do have an air filter in the tank, but the gasping behavior you've noticed makes me think perhaps they fish aren't getting enough O2. Most major test kit brands have a conversion chart to measure oxygen levels - I personally use the Tetra brand kit, but I don't think it matters too much. Just stay away from the "dip stick" type test kits, as they are pretty unreliable. Aside from that, I'm thinking perhaps a toxin other than ammonia, nitrite or nitrite has found its way into the water - I say this because of the suddenness of the fishes' death. Can you think of *anything* (from cleaning supplies to air fresheners, for example), that could possibly be contaminating the water? I don't know if it will help, but you could try additional water changes and perhaps looking into a PolyFilter - filter media that removes lots of unwanted toxins, from phosphates to ammonia. (That's a shot in the dark, though - it's all I can think of!) You may be correct in thinking your fish weren't altogether healthy when you purchased them. Any idea how long they were living at the fish store? That's good question to ask - the longer the better, but you won't always get that lucky. I have never personally kept neon tetras, but from what I understand, they can be fragile. You did well to slowly acclimate them when you brought 'em home, and as I said above, did everything else according to the "rules".  With regards to medicating, I don't think I'd go there, especially since you don't see any observable signs of illness or lacerations. You may indeed do more harm than good - I never recommend using meds just for the sake of it, and it's always best to narrow down what's going on before taking a "shot in the dark" approach to medicating fish. Do check on the oxygen levels, and think about possible water contaminants. In the meantime, keep those water levels pristine, and hopefully the two survivors will be OK. I'll cross my fingers for you!  Good luck, Jorie> 
Re: Dying neon tetras
Hiya Jorie, <Good morning, Charlotte.> Thanks so much for your reply, I don't think they had been in the shop long now I think about it, because we had been in a couple of times in the days before to get fish food and other things, and hadn't noticed them when we had a look around.  I can't think of anything I might have accidentally exposed them to (even been careful not to wear perfume on my wrists in case I need to dive in!) but maybe I'm forgetting something. I'll definitely look into a PolyFilter, that sounds a good idea - want to do my best for them, felt awful for the first ones. Have named the other two Crusoe and Friday as they are so far survivors! Thanks for all your advise, you've been really helpful, I'll keep you posted, but so far so good.  Charlotte  <Glad to hear Crusoe and Friday are doing well! I know neon tetras are an extremely popular choice with hobbyists, but my understanding is that they are remarkably fragile. Additionally, I believe they are strictly wild-caught (as opposed to tank raised), which always increases the chances of a fish not acclimating well into captivity. It sounds as though you are doing absolutely everything you can to keep these little guys happy and healthy, so I wouldn't beat yourself up over it too much. Some things just aren't within our control! Best of luck, Jorie> 

Pop Eye on a Silver Dollar 8/3/05 Hi, I am Janet. I have a 55 gal fresh with 10 white clouds, 4 black tetra, 2 spotted Cory cats, 2 dwarf gouramis, 1 blue magic dwarf Gourami (the other died in this heyday I have been having) , one goldfish, one black moor, 2 scissortail Rasbora and 2 six or seven year old Silver Dollars that were given to me by a friend when his wife died. They were her babies. Hi Oh Silver came down with Popeye then a god awful case of dropsy. I put in Melafix for the seven day prescribed and Hi Oh didn't really improve much. I changed out 25% of the tank, put in Stress Coat and Stress Zyme and some Methylene Blue. Hi Oh looked bad yet. I went searching on the internet and found your site with salt treatments for these diseases. I didn't have Aquarium Salts but another site said Kosher Salt would do too. So I mixed up the salt (one gal to 4 teasp Kosher salt) popped Hi in and watched him for distress. After 3 min.s (of the 5, unless distressed) I thought he looked like he wanted out. So I put him in the tank. Next morning HE LOST ALL THE POPEYE AND MOST OF THE SWELLING!! I did a test and found my nitrates were 160 so I did another water change out of nearly 50%. Put in Stress Coat and Stress Zyme and Meth blue. My test today shows PH 6.0, Ammonia 0ppm, Nitrite 0ppm and finally, Nitrate 0ppm. It seems Hi Oh is getting Popeye again and I think his pal, Long John Silver is too. Oh, I put in new carbon filters in case of something in the water affected the old new filters I had in. Hi looks great other then that. A very small swelling on his cap (above his eyes/face), looks somewhat silver in most places, eating, swimming all about and with his buddy. My question is should I start over and put the two in a hospital tank and treat with Melafix again or just do salt dips again? How many times can I salt dip a fish and at what frequency.... daily, every other day, ???? Salt seems to best work to bring down swelling. I have been fighting this for 3 weeks now and Hi is still here. He does sit stationary a bit crooked but he swims great. I think he can see yet out of his eyes. So far Long John is puffy in one eye.   This whole mess started with fish from PetSmart and putting their water in my tank. I didn't know not too since I read to do it in a dumb book, only to find out NEVER put water in another tank. I have NEVER tested water before so that is all new to me too but I desperately want to save the boys. Please help me : ( < The high nitrates are stressing your silver dollars. Keeping them down to under 25 ppm will be very beneficial. I have found that salt dose reduce the swelling and some fish do recover enough to be cured from this internal bacterial infection but just don't seem to be cured. I would recommend Metronidazole to treat the infected fish in a hospital tank so it won't affect the good bacteria needed to break down the fish waste.-Chuck>

Become a Sponsor Features:
Daily FAQs FW Daily FAQs SW Pix of the Day FW Pix of the Day New On WWM
Helpful Links Hobbyist Forum Calendars Admin Index Cover Images
Featured Sponsors: