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FAQs on Characoids/Tetras & Relatives Social Disease

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

Most Characoids are schooling species... NEED to be kept in a group... in small volumes, odd numbers of individuals are best.


Minor Serpae Tetra fin rot?     11/2/14
Greetings. I have a 55-gallon aquarium that we set up 2 years ago & has been stable and disease-free. Water parameters are: ammonia = 0, nitrite = 0, nitrate = 30, phosphorous = 0. I do a water change every week. We have live plants (water sprite wisteria). The inhabitants are 2 Bristlenose Plecos, 8 black-skirt tetras, 8 white-skirt tetras, 11 minor Serpae tetras, and about 6 apple snails. The Serpae tetras were introduced about 2 weeks ago and my quarantine tank currently is housing some baby Gold Gouramis, so
I chose not to quarantine them. I know I should have, but I have never had any problem with the tetras from this source. A bad decision on my part, but anyway, may I explain the problem to you...?
<Fire away.>
Oddly enough, the other fish in the tank seem to be still healthy and unaffected by this disease bothering the serape tetras. It is the strangest thing I have ever seen. The first sign is a very pale area where the dorsal
fin meets their body. It's very clearly delineated and easy to see against their red-orange background. Soon after that, the dorsal fin degenerates and the fish seems to die within a day or two after they reach that stage.
They don't seem swollen and neither do they show any other signs of illness. I have never seen fin rot behave like this or fin rot that just affects one species of tetra. Today, I got some API Triple Sulfa and am
planning on giving them the entire course of treatment as directed by the manufacturer. Do you think that I am on the right track here? Please advise and thank you so much for your time and any comments you may have for me.
<Serpae Tetras are notorious fin-nippers, so one explanation is that they're fighting within the group (which they do, especially when feeding) and damaging one another. When feeding they have a feeding frenzy
behaviour, but will also bully weaker specimens, even killing them. Usually they attack other fish too, but the Black/White Skirt Tetras (both Gymnocorymbus ternetzi) are pretty pushy, fast-moving little fish
themselves, and may be holding their own just fine. Gouramis, though, are easy targets so I wouldn't mix them. This said, it is rare for Finrot to kill fish within a couple days. Adding more Serpae tetras might help, by
spreading out any aggression, but before doing that you'd want to observe the Serpae Tetras and see if they're chasing or nipping each other. If they are fighting, adding a few more could be a good move. Alternatively, you might simply have a "bad batch" of Serpae Tetras, in which case medicating for Finrot might stabilise things, giving you time to see if they can be saved. If the fish get better, then no harm done. If they eventually all die, I'd recommend not buying Serpae Tetras again. Although cheap and usually extremely hardy, they aren't well behaved fish, and there are better alternatives such as Red Phantom Tetras out there.>
<Cheers, Neale.>

Tetra issue. Moenkhausia injured, living solo 11/14/11
Well I'm not entirely sure what to do about this fish. Early September, I was placed in charge of a 55 gallon tank here at my school, first thing I did was get the water levels how they should be.
<Good start>
There were small amounts of ammonia and nitrite (less than .5 ppm, but I was not happy with that)
<Me neither>

and the KH was non existent while the GH was way over 30 (I stopped counting is was so bad). This tank is stocked with tetras, patties, barbs,
<Mmm, what species are these Barbs?>
mollies and Pleco. Everything seemed just fine, I started putting AquaSafe in the tank (slowly to ensure the fish acclimated correctly, they had been adding straight tap water for over a year and the Ammonia and Nitrite levels here are insane).
<In the source water? This is bad... would not use for my potable purposes w/o running through a reverse osmosis device first>
Everything was fine, we lost one fish (had been purchased from Wal-Mart and it looked slightly discolored when I started). Well, about a week ago now, I noticed that there was this huge blackish/brown spot on the right side of the Lamp Eye Tetra. It was swollen, so I pulled the fish and it has been in quarantine ever since. I watched it the first couple days and smaller spots began to appear on other areas of the fish, so I started adding Rid-Ich
<Mmm, I wouldn't do this. The active ingredients are too harsh... Formalin and Malachite Green>
(which has worked on everything I've ever come across without issues) and the smaller spots went away, but the swelling on that one spot has continued. I've never had anything require treatment for more than four days, so I stopped treating yesterday.
This spot now has some slight red around the edges of it now.
The fish is eating and swimming fine, but I'm not sure what else to do.
<Nothing... other than providing good care... water quality and nutrition wise... Likely this Tetra has been bruised... perhaps from an altercation w/ another fish here, maybe just a "bump" into something hard. Will heal on its own in time>
Nothing has changed in the tank in a month and a half and I even added a female Molly and a Dwarf Gourami to the tank (quarantined and added after the tetra had been removed, so they did not cause this). This fish is about 2 inches nose to tail and they are expecting me to magically cure this fish, but I'm unsure what to do for it right now. At this point, I don't think it's Black Spot. The only time I seen something even close to this before was on a female guppy who developed an internal tumor, was black and swollen, she died within a month.
Current tank stats:
Ammonia: 0, Nitrite: 0, Nitrate: 5, KH: 2, GH: 29, pH: 7.0, Temp: 72-74 degrees (depends on if the lights are on).
<Mmm, given the mix of species, this water is fine>
Thank you!
Confused Student.
<And a note re this fish, Moenkhausia spp. are strongly schooling species.
Really will do much better kept in a small group. I'd add a few more. Bob Fenner>

Question about spot on neon's mouth 3/26/08 Hi folks, I have a 10-gallon tank with a male Betta, two neon tetras, a frog, and two algae eaters (the kind that stay little, not sure of the name). They have all lived together for several months. I clean the tank every other week, this usually keeps the nitrates under 10. <Neons need to be in groups of 6 or more; in smaller groups they are stressed and unhappy. Please note that fish couldn't care less about cute names. But what they want is that you work around their biological needs. In the case of Neons, that means company! Keeping them in too-small a group is animal cruelty, however you choose to rationalise it.> One of the Neons (Zippity) has a dark spot on his lower lip. I recently had a problem with stringy algae and thought he may have gotten some stuck on his mouth, but it hasn't come off in a couple of days. He is able to eat. Should I put him in the hospital tank in case he is sick and could pass it along to the others? <No. It may simply be physical damage, in which case it will heal. But do also be aware that things like Mouth Fungus and Finrot can start as small blisters or sores. So as ever, check your nitrite level before you do anything else.> Also, should I be adding aquarium salt to the tank? <No. Almost all fish diseases come down to water quality issues. Almost none come down to not using salt!> I don't now because I thought I read that Neons don't like salt, but did read that it's good for disease prevention. <They don't and it isn't.> Thank you! Alice <Cheers, Neale.>

Re: question about spot on neon's mouth Thank you for the advice. I will keep a close eye on the spot. The two Neons are the last two from a school - I will make sure they find a new home with other Neons as soon as he recovers. <Very good. Good luck, Neale.>

Tetra Not His Old Self  - 1/6/06 Hello again. Thanks for the information you sent me! I have one other question for you. I got a small fish from a friend last year and It looks a lot like a Tetra. The fish was wobbling while trying to swim so I place him in a hospital tank for about 5 days or so and treated him with Erythromycin 200mg and he is swimming a lot better and his breathing is good. My problem is when I placed him back in my regular tank he stays about 4 or 5 inches from the top of my 60 gal!  Should I treat him with something else or any ideas you can come up with? Thanks again Ian < I am not a big fan of blindly treating fish. The sounds more like an accumulation problem and not really an illness. Reduce the lighting and see if he starts to mingle with the other fish after awhile. Give him a little time to get back in the pecking order.-Chuck>

Upside down catfish and skinny tetras  09/13/2005 Hi everyone at WWM, <Hi, Cobina!> I am enjoying your site and I have found some information that I found interesting and will hopefully put to good use. <Ahh, glad to hear it.> I have a couple of questions, but first I wanted to give you a quick rundown on the occupants of my ten gallon tank. <Okay.> This is my first tank and I have had it for less than a year. The tank came with one painted tetra (pixie) and one upside-down catfish (Dixie, I know creative huh?). So I got a couple more painted tetras and one more ud catfish for company and tried to give them lots of hiding places (as the person before had just a bare tank). <Some words of caution, here....  "Painted" tetras are typically tetras that have been artificially dyed; this process is quite stressful to fish and can be quite harmful.  I believe that fish that go through the dyeing process usually are very susceptible to disease.  Please don't support this by purchasing any more of these "damaged" fish; rather, give yours the best care that you can to help them recover.  With luck, they will survive and eventually regain their natural state and color.  I would also like to caution you to the size of upside-down catfish; please read here:   http://www.wetwebmedia.com/FWSubWebIndex/mochokids.htm > Recently (almost three months ago) I found a beautiful polka-dotted loach, and a female Betta and added them to the tank. <Getting a bit full, there....  Any plans for a larger tank?  Might start thinking about it if space and money allow.> For a long time they seemed to get along very well. The Betta seemed to almost become another member of the tetra family, as she swam around with them often, and although the loach was kind of pushy under the wood with the catfish, he didn't seem to nip at the others (other than the first day when I assume it was him that ripped the back fin of one of my tetras). <Actually, I would guess that another tetra was responsible....  but it may have been the loach.  Many loaches (not all!) can get quite aggressive.> Then a few weeks ago the water got cloudy shortly after a regular water change and I couldn't get it unclouded. <Possibly a sign that your tank just has too much fish/bioload for its capacity.> Then when I realized that my daughter had inadvertently switched the washing pail with the fish pail, I was absolutely mortified. <Yikes!> But before I realized that my Betta had committed suicide and jumped out of the tank while we were asleep and we didn't find her until the next day (poor thing). Also during this time my loach was getting quite aggressive and nipping at the other fish, and two of my tetras are getting really skinny. <Possibly long-term results of being dyed....  Also, I begin to suspect poor environmental conditions.> I finally got the water in order and started giving my bottom feeders sinking pellets so that the loach would hopefully stay at the bottom and not bother the tetras. The catfish didn't seem to be particularly interested in the pellets, as they would go right past (or over) them while scouring the bottom of the tank.  I thought maybe the tetras were stressed and that's why they got thin. But after reading your site, I am thinking that maybe they have internal parasites. <A possibility, but in all honesty, I would look to environmental causes first.  Please be testing for ammonia, nitrite and nitrate....  Maintain ammonia and nitrite at ZERO, and nitrate below 20ppm.> I am just beside myself with guilt and worry. They don't seem to be getting any fatter after having good water. If it is parasites, is there any kind of treatment? I don't want to see them just wither away to nothing. <First, test the water, and go from there.> Another thing I was wondering is that Dixie (my first ud catfish) sometimes gets a big belly when he/she eats a lot. But my goodness, his belly is at least twice as large as I have ever seen it. It is even sticking out on the sides. He seems to be quite happy though, as far as I can tell. Then I thought maybe he's pregnant. Is this possible? I would love to have baby catfish, but I don't know if they even breed in captivity, and I am certain that I would have to maybe set them up in another tank so the loach wouldn't get at the fry. <I rather doubt that it's a pregnancy issue - but if it is, there will be a lot of research you'll need to do prior to being capable of raising the fry....  Figure out what species they are, and start searching.> Or maybe he's just super fat because maybe he pigged out on the pellets after I went to bed. <Entirely possible.> So my questions are really: 1) Do you think that my tetras have internal parasites, and if not what do you think it might be, and if you think they are parasites how do I treat them. I don't have another tank to put them in to make a sick tank. I have a one gallon tank that I have a male Betta in, but it doesn't have any filter system of any kind. What are your thoughts? <Currently, there are too many possibilities to narrow down what might ail the tetras.  It may be completely outside of any ability to treat, if it is a health issue related to the dyeing process.> and 2) Do you think my ud catfish is pregnant, or just really fat from pigging out on pellets, or worse I hope he isn't sick. <Hopefully not sick.  Just observe closely for a while, and by all means test your water!> Anyway, I know it was a long explanation, but I wanted to make sure you got all the pertinent information that you may need to assess my poor fishes. <The more information, the better.  Thank you for being so thorough.> I really enjoyed your website, and was very encouraged by the amount of information there. <I'm very glad to hear this!> I really appreciate the fact that you accept questions and that you take the time and effort to share your expertise with other fish lovers like me who are sort of new to the game. <Thank you very much for the kind words - and chin up, whatever the outcome for the tetras, I am confidant that they are in good hands with your compassionate outlook.> Thanks again.  Sincerely,  -Cobina. <Wishing you well,  -Sabrina>
Upside down catfish and skinny tetras - II - 09/15/2005
Hi Sabrina, <Hello!> Thanks for all of your advise, but I am sad to say that the two tetras died the same night that I wrote the email. I found them in the morning. <I'm so sorry to hear this, Cobina....> I had the ammonia, nitrate, nitrite tested a few days before they died and they were fine. <It doesn't take long for water quality to go from fine to lousy....  It would be a good idea to get your own test kits (preferably liquid reagent kits instead of dipstick-type) so you can test whenever necessary.> And I even had the water tested for phosphate because of the possible soap poisoning but that was fine too. A week and a half and two water changes earlier the ammonia was high.  Now after taking out the fish yesterday, the water was really stinky (not normal), <Likely water quality had declined from the decaying fish.> so I did a partial water change and scrubbed down the rocks from inside the tank. It smells better now, but I need to get it tested just in case things are funny. <Agreed.> The catfish have been hiding so I'm not entirely sure if Dixie's belly has gone down, but I suspect that it has. Thanks for the link about the ud catfish. You startled me there, I thought that you meant that they would get really big like the Plecos do, but they say they only get to about four inches. <A four inch fish, with so many tankmates, is a little large for a 10 gallon tank, though....  As these guys grow (and they will, though perhaps slowly), you will want to consider something larger.> I don't know why mine aren't growing. Dixie, my first one is at least two years old (and is maybe two inches long if that) <Uncommon....  Nutritional deficiency or poor water quality can inhibit a fish's growth and "stunt" it; do you know what conditions she had with her previous owner?> and the other newer one, I got last October or November, and who knows how old she was when I got her, she is slightly (but not much) bigger than Dixie. <It's all just a matter of time.> Dixie came to me with stumps instead of fins, I guess being in a bare tank with only red rocks and one tetra, the tetra probably chewed them off. But now they have grown back. They aren't as full as the other catfish, but at least now he has fins. <A major improvement, to be sure!  And a sign that your care is a big step up from what he'd had, perhaps.> As far as overcrowding, I thought I was doing good. I had up to seven at one time but usually it has been five or six. <Seven?  Five?  Six?  What?  Fish?> The tetras are probably an inch long each, the two catfish together are four, that makes 7 and the new loach is probably three inches so that makes 10. <Aim for their adult sizes, and add those instead....  Furthermore, the cats may get territorial as they grow (though not really "aggressive", I don't think), so a bigger space again might be good.> I guess I didn't think the catfish were that big. They just seem so small. It was only the five (the three tetras and the two catfish) for the longest time until a couple of months ago. Maybe I should cut it back to that again. <Or just get addicted to fishkeeping and get more or larger tanks (grin)!> I am trying to think about what I can replace my tetras with (I still have one left that I want to be able to integrate with the new fish). and I think I may have to find a new home for the loach, he is beautiful to watch but he is possibly too pushy with the catfish, especially if I want to try making catfish babies in the future (if that is even possible). <Agreed, wholeheartedly.  The loach's behaviour will not improve.  I would try to find him a new home if possible.> I would Love to get a bigger tank, or maybe run this one and then a larger one with other fish. I have plans to do that when the funds allow for it. <Sounds excellent.> Anyway, I wanted to thank you again for your advice and getting back to me so soon. <Sure thing.> If you have any suggestions on what you think might be a good tankmate for the catfish and my lone tetra, I would be delighted to hear your suggestions. <Other tetras might be a good plan, since they are schooling fish - but please do try to stay away from dyed fish.> Thanks again. <No problem> Take care, and know that your advice goes far with us new fish lovers. <Thank you for this - you are very kind!> Sincerely,  -Cobina <Wishing you well,  -Sabrina>

Pregnant neon  9/5/05 Hi, Please help-I think I've done something awful. I set up my new tank yesterday, but because the above neon seemed to be harassed by other fish I put the fish in the new tank.  She seems very stressed, swimming in jerky movements, in circles. I have turned the light off .  My predicament is: Should I put the fish back with the others or put another neon in for company? Please advise. <I would add another neon to this ones tank> Regards and thanks for your assistance Jacqui <Bob Fenner>

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